/* * sample-store.c -- * * FastCGI example program using fcgi_stdio library * * * Copyright (c) 1996 Open Market, Inc. * * See the file "LICENSE.TERMS" for information on usage and redistribution * of this file, and for a DISCLAIMER OF ALL WARRANTIES. * * * sample-store is a program designed to illustrate one technique * for writing a high-performance FastCGI application that maintains * permanent state. It is real enough to demonstrate a range of issues * that can arise in FastCGI application programming. * * sample-store implements per-user shopping carts. These carts are kept * in memory for speed but are backed up on disk for reliability; the * program can restart at any time, affecting at most one request. Unlike * CGI applications, the performance impact of sample-store's disk * use is negligible: no I/O for query requests, no reads and one write * for a typical update request. * * sample-store's on-disk representation is extremely simple. The * current state of all shopping carts managed by a process is kept * in two files, a snapshot and a log. Both files have the same format, * a sequence of ASCII records. On restart the current state is restored * by replaying the snapshot and the log. When the log grows to a certain * length, sample-store writes a new snapshot and empties the log. * This prevents the time needed for restart from growing without * bound. * * Since users "visit" Web sites, but never "leave", sample-store * deletes a shopping cart after the cart has been inactive * for a certain period of time. This policy prevents sample-store's * memory requirements from growing without bound. * * sample-store operates both as a FastCGI Responder and as an * Authorizer, showing how one program can play two roles. * * The techniques used in sample-store are not specific to shopping * carts; they apply equally well to maintaining all sorts of * information. * */ #ifndef lint static const char rcsid[] = "$Id: sample-store.c,v 1.2 1999/01/30 22:27:34 roberts Exp $"; #endif /* not lint */ #include "fcgi_stdio.h" /* FCGI_Accept, FCGI_Finish, stdio */ #include /* malloc/free, getenv, strtol */ #include /* strcmp, strncmp, strlen, strstr, strchr */ #include /* Tcl_*Hash* functions */ #include /* time, time_t */ #include /* assert */ #include /* errno, ENOENT */ #include /* readdir, closedir, DIR, dirent */ #include /* fsync */ #if defined __linux__ int fsync(int fd); #endif /* * sample-store is designed to be configured as follows (for the OM server): * * SI_Department SampleStoreDept -EnableAnonymousTicketing 1 * Region /SampleStore/* { SI_RequireSI SampleStoreDept 1 } * * Filemap /SampleStore $fcgi-devel-kit/examples/SampleStore * AppClass SampleStoreAppClass \ * $fcgi-devel-kit/examples/sample-store \ * -initial-env STATE_DIR=$fcgi-devel-kit/examples/SampleStore.state \ * -initial-env CKP_THRESHOLD=100 \ * -initial-env CART_HOLD_MINUTES=240 \ * -processes 2 -affinity * Responder SampleStoreAppClass /SampleStore/App * AuthorizeRegion /SampleStore/Protected/* SampleStoreAppClass * * sample-store looks for three initial environment variables: * * STATE_DIR * When sample-store is run as a single process without affinity * this is the directory containing the permanent state of the * process. When sample-store is run as multiple processes * using session affinity, the state directory is * $STATE_DIR.$FCGI_PROCESS_ID, e.g. SampleStore.state.0 * and SampleStore.state.1 in the config above. The process * state directory must exist, but may be empty. * * CKP_THRESHOLD * When the log grows to contain this many records the process * writes a new snapshot and truncates the log. Defaults * to CKP_THRESHOLD_DEFAULT. * * CART_HOLD_MINUTES * When a cart has not been accessed for this many minutes it * may be deleted. Defaults to CART_HOLD_MINUTES_DEFAULT. * * The program is prepared to run as multiple processes using * session affinity (illustrated in config above) or as a single process. * * The program does not depend upon the specific URL prefix /SampleStore. * */ /* * This code is organized top-down, trying to put the most interesting * parts first. Unfortunately, organizing the program in this way requires * lots of extra declarations to take care of forward references. * * Utility functions for string/list processing and such * are left to the very end. The program uses the Tcl hash table * package because it is both adequate and readily available. */ #ifndef FALSE #define FALSE (0) #endif #ifndef TRUE #define TRUE (1) #endif #ifndef max #define max(a,b) ((a) > (b) ? (a) : (b)) #endif #define Strlen(str) (((str) == NULL) ? 0 : strlen(str)) void panic(char *format, char *arg1, char *arg2, char *arg3, char *arg4, char *arg5, char *arg6, char *arg7, char *arg8); static void *Malloc(size_t size); static void Free(void *ptr); static char *StringNCopy(char *str, int strLen); static char *StringCopy(char *str); static char *StringCat(char *str1, char *str2); static char *StringCat4(char *str1, char *str2, char *str3, char *str4); static char *QueryLookup(char *query, char *name); static char *PathTail(char *path); typedef struct ListOfString { char *head; struct ListOfString *tail; } ListOfString; static char *ListOfString_Head(ListOfString *list); static ListOfString *ListOfString_Tail(ListOfString *list); static int ListOfString_Length(ListOfString *list); static int ListOfString_IsElement(ListOfString *list, char *element); static ListOfString *ListOfString_AppendElement( ListOfString *list, char *element); static ListOfString *ListOfString_RemoveElement( ListOfString *list, char *element); static int IntGetEnv(char *varName, int defaultValue); static void Initialize(void); static void PerformRequest(void); static void GarbageCollectStep(void); static void ConditionalCheckpoint(void); /* * A typical FastCGI main program: Initialize, then loop * calling FCGI_Accept and performing the accepted request. * Do cleanup operations incrementally between requests. */ void main(void) { Initialize(); while(FCGI_Accept() >= 0) { PerformRequest(); FCGI_Finish(); GarbageCollectStep(); ConditionalCheckpoint(); } } /* * All the global variables */ typedef struct CartObj { int inactive; /* This cart not accessed since mark */ ListOfString *items; /* Items in cart */ } CartObj; static Tcl_HashTable *cartTablePtr; /* Table of CartObj, indexed by userId */ static Tcl_HashTable cartTable; static char *fcgiProcessId; /* Id of this process in affinity group */ static char *stateDir; /* Path to dir with snapshot and log */ char *snapshotPath, *logPath; /* Paths to current snapshot and log */ static int generation; /* Number embedded in paths, inc on ckp */ static FILE *logFile = NULL; /* Open for append to current log file */ static int numLogRecords; /* Number of records in current log file */ static int checkpointThreshold; /* Do ckp when numLogRecords exceeds this */ static int purge = TRUE; /* Cart collector is removing inactives */ static time_t timeCartsMarked; /* Time all carts marked inactive */ static int cartHoldSeconds; /* Begin purge when this interval elapsed */ #define STATE_DIR_VAR "STATE_DIR" #define PID_VAR "FCGI_PROCESS_ID" #define CKP_THRESHOLD_VAR "CKP_THRESHOLD" #define CKP_THRESHOLD_DEFAULT 200 #define CART_HOLD_MINUTES_VAR "CART_HOLD_MINUTES" #define CART_HOLD_MINUTES_DEFAULT 300 #define SNP_PREFIX "snapshot" #define LOG_PREFIX "log" #define TMP_SNP_NAME "tmp-snapshot" #define LR_ADD_ITEM "Add" #define LR_REMOVE_ITEM "Rem" #define LR_EMPTY_CART "Emp" static char *MakePath(char *dir, char *prefix, int gen); static void AnalyzeStateDir( char *dir, char *prefix, int *largestP, ListOfString **fileListP); static int RecoverFile(char *pathname); static void Checkpoint(void); /* * Initialize the process by reading environment variables and files */ static void Initialize(void) { ListOfString *fileList; int stateDirLen; /* * Process miscellaneous parameters from the initial environment. */ checkpointThreshold = IntGetEnv(CKP_THRESHOLD_VAR, CKP_THRESHOLD_DEFAULT); cartHoldSeconds = IntGetEnv(CART_HOLD_MINUTES_VAR, CART_HOLD_MINUTES_DEFAULT)*60; /* * Create an empty in-memory shopping cart data structure. */ cartTablePtr = &cartTable; Tcl_InitHashTable(cartTablePtr, TCL_STRING_KEYS); /* * Compute the state directory name from the initial environment * variables. */ stateDir = getenv(STATE_DIR_VAR); stateDirLen = Strlen(stateDir); assert(stateDirLen > 0); if(stateDir[stateDirLen - 1] == '/') { stateDir[stateDirLen - 1] = '\000'; } fcgiProcessId = getenv(PID_VAR); if(fcgiProcessId != NULL) { stateDir = StringCat4(stateDir, ".", fcgiProcessId, "/"); } else { stateDir = StringCat(stateDir, "/"); } /* * Read the state directory to determine the current * generation number and a list of files that may * need to be deleted (perhaps left over from an earlier * system crash). Recover the current generation * snapshot and log (either or both may be missing), * populating the in-memory shopping cart data structure. * Take a checkpoint, making the current log empty. */ AnalyzeStateDir(stateDir, SNP_PREFIX, &generation, &fileList); snapshotPath = MakePath(stateDir, SNP_PREFIX, generation); RecoverFile(snapshotPath); logPath = MakePath(stateDir, LOG_PREFIX, generation); numLogRecords = RecoverFile(logPath); Checkpoint(); /* * Clean up stateDir without removing the current snapshot and log. */ while(fileList != NULL) { char *cur = ListOfString_Head(fileList); if(strcmp(snapshotPath, cur) && strcmp(logPath, cur)) { remove(cur); } fileList = ListOfString_RemoveElement(fileList, cur); } } static char *MakePath(char *dir, char *prefix, int gen) { char nameBuffer[24]; sprintf(nameBuffer, "%s.%d", prefix, gen); return StringCat(dir, nameBuffer); } static void ConditionalCheckpoint(void) { if(numLogRecords >= checkpointThreshold) { Checkpoint(); } } static void WriteSnapshot(char *snpPath); static void Checkpoint(void) { char *tempSnapshotPath, *newLogPath, *newSnapshotPath; /* * Close the current log file. */ if(logFile != NULL) { fclose(logFile); } /* * Create a new snapshot with a temporary name. */ tempSnapshotPath = StringCat(stateDir, TMP_SNP_NAME); WriteSnapshot(tempSnapshotPath); ++generation; /* * Ensure that the new log file doesn't already exist by removing it. */ newLogPath = MakePath(stateDir, LOG_PREFIX, generation); remove(newLogPath); /* * Commit by renaming the snapshot. The rename atomically * makes the old snapshot and log obsolete. */ newSnapshotPath = MakePath(stateDir, SNP_PREFIX, generation); rename(tempSnapshotPath, newSnapshotPath); /* * Clean up the old snapshot and log. */ Free(tempSnapshotPath); remove(snapshotPath); Free(snapshotPath); snapshotPath = newSnapshotPath; remove(logPath); Free(logPath); logPath = newLogPath; /* * Open the new, empty log. */ logFile = fopen(logPath, "a"); numLogRecords = 0; } /* * Return *largestP = the largest int N such that the name prefix.N * is in the directory dir. 0 if no such name * *fileListP = list of all files in the directory dir, * excluding '.' and '..' */ static void AnalyzeStateDir( char *dir, char *prefix, int *largestP, ListOfString **fileListP) { DIR *dp; struct dirent *dirp; int prefixLen = strlen(prefix); int largest = 0; int cur; char *curName; ListOfString *fileList = NULL; dp = opendir(dir); assert(dp != NULL); while((dirp = readdir(dp)) != NULL) { if(!strcmp(dirp->d_name, ".") || !strcmp(dirp->d_name, "..")) { continue; } curName = StringCat(dir, dirp->d_name); fileList = ListOfString_AppendElement(fileList, curName); if(!strncmp(dirp->d_name, prefix, prefixLen) && (dirp->d_name)[prefixLen] == '.') { cur = strtol(dirp->d_name + prefixLen + 1, NULL, 10); if(cur > largest) { largest = cur; } } } assert(closedir(dp) >= 0); *largestP = largest; *fileListP = fileList; } static int DoAddItemToCart(char *userId, char *item, int writeLog); static int DoRemoveItemFromCart(char *userId, char *item, int writeLog); static int DoEmptyCart(char *userId, int writeLog); /* * Read either a snapshot or a log and perform the specified * actions on the in-memory representation. */ static int RecoverFile(char *pathname) { int numRecords; FILE *recoveryFile = fopen(pathname, "r"); if(recoveryFile == NULL) { assert(errno == ENOENT); return 0; } for(numRecords = 0; ; numRecords++) { char buff[128]; char op[32], userId[32], item[64]; int count; char *status = fgets(buff, sizeof(buff), recoveryFile); if(status == NULL) { assert(feof(recoveryFile)); fclose(recoveryFile); return numRecords; } count = sscanf(buff, "%31s %31s %63s", op, userId, item); assert(count == 3); if(!strcmp(op, LR_ADD_ITEM)) { assert(DoAddItemToCart(userId, item, FALSE) >= 0); } else if(!strcmp(op, LR_REMOVE_ITEM)) { assert(DoRemoveItemFromCart(userId, item, FALSE) >= 0); } else if(!strcmp(op, LR_EMPTY_CART)) { assert(DoEmptyCart(userId, FALSE) >= 0); } else { assert(FALSE); } } } static void WriteLog(char *command, char *userId, char *item, int force); /* * Read the in-memory representation and write a snapshot file * that captures it. */ static void WriteSnapshot(char *snpPath) { Tcl_HashSearch search; Tcl_HashEntry *cartEntry; ListOfString *items; char *userId; logFile = fopen(snpPath, "w"); assert(logFile != NULL); cartEntry = Tcl_FirstHashEntry(cartTablePtr, &search); for(cartEntry = Tcl_FirstHashEntry(cartTablePtr, &search); cartEntry != NULL; cartEntry = Tcl_NextHashEntry(&search)) { userId = Tcl_GetHashKey(cartTablePtr, cartEntry); for(items = ((CartObj *) Tcl_GetHashValue(cartEntry))->items; items != NULL; items = ListOfString_Tail(items)) { WriteLog(LR_ADD_ITEM, userId, ListOfString_Head(items), FALSE); } } fflush(logFile); fsync(fileno(logFile)); fclose(logFile); } static void WriteLog(char *command, char *userId, char *item, int force) { fprintf(logFile, "%s %s %s\n", command, userId, item); ++numLogRecords; if(force) { fflush(logFile); fsync(fileno(logFile)); } } static int RemoveOneInactiveCart(void); static void MarkAllCartsInactive(void); /* * Incremental garbage collection of inactive shopping carts: * * Each user access to a shopping cart clears its "inactive" bit via a * call to MarkThisCartActive. When restart creates a cart it * also marks the cart active. * * If purge == TRUE, each call to GarbageCollectStep scans for and removes * the first inactive cart found. If there are no inactive carts, * GarbageCollectStep marks *all* carts inactive, records the time in * timeCartsMarked, and sets purge = FALSE. * * If purge == FALSE, each call to GarbageCollectStep checks the * elapsed time since timeCartsMarked. If the elapsed time * exceeds a threshold, GarbageCollectStep sets purge = TRUE. */ static void GarbageCollectStep(void) { if(purge) { if(!RemoveOneInactiveCart()) { MarkAllCartsInactive(); timeCartsMarked = time(NULL); purge = FALSE; } } else { int diff = time(NULL)-timeCartsMarked; if(diff > cartHoldSeconds) { purge = TRUE; } } } static int RemoveOneInactiveCart(void) { Tcl_HashSearch search; Tcl_HashEntry *cartEntry; CartObj *cart; char *userId; cartEntry = Tcl_FirstHashEntry(cartTablePtr, &search); for(cartEntry = Tcl_FirstHashEntry(cartTablePtr, &search); cartEntry != NULL; cartEntry = Tcl_NextHashEntry(&search)) { cart = Tcl_GetHashValue(cartEntry); if(cart->inactive) { userId = Tcl_GetHashKey(cartTablePtr, cartEntry); DoEmptyCart(userId, TRUE); return TRUE; } } return FALSE; } static Tcl_HashEntry *GetCartEntry(char *userId); static void MarkAllCartsInactive(void) { Tcl_HashSearch search; Tcl_HashEntry *cartEntry; CartObj *cart; cartEntry = Tcl_FirstHashEntry(cartTablePtr, &search); for(cartEntry = Tcl_FirstHashEntry(cartTablePtr, &search); cartEntry != NULL; cartEntry = Tcl_NextHashEntry(&search)) { cart = Tcl_GetHashValue(cartEntry); cart->inactive = TRUE; } } static void MarkThisCartActive(char *userId) { Tcl_HashEntry *cartEntry = GetCartEntry(userId); CartObj *cart = Tcl_GetHashValue(cartEntry); cart->inactive = FALSE; } #define OP_DISPLAY_STORE "DisplayStore" #define OP_ADD_ITEM "AddItemToCart" #define OP_DISPLAY_CART "DisplayCart" #define OP_REMOVE_ITEM "RemoveItemFromCart" #define OP_PURCHASE "Purchase" static void DisplayStore( char *scriptName, char *parent, char *userId, char *processId); static void AddItemToCart( char *scriptName, char *parent, char *userId, char *processId, char *item); static void DisplayCart( char *scriptName, char *parent, char *userId, char *processId); static void RemoveItemFromCart( char *scriptName, char *parent, char *userId, char *processId, char *item); static void Purchase( char *scriptName, char *parent, char *userId, char *processId); static void InvalidRequest(char *code, char *message); static void Authorize(char *userId); /* * As a Responder, this application expects to be called with the * GET method and a URL of the form * * http:///?op=&item= * * The application expects the SI_UID variable to provide * a user ID, either authenticated or anonymous. * * The application expects the directory *containing* * to contain various static HTML files related to the application. * * As an Authorizer, the application expects to be called with * SID_UID and URL_PATH set. */ static void PerformRequest(void) { char *method = getenv("REQUEST_METHOD"); char *role = getenv("FCGI_ROLE"); char *scriptName = PathTail(getenv("SCRIPT_NAME")); char *parent = ""; char *op = QueryLookup(getenv("QUERY_STRING"), "op"); char *item = QueryLookup(getenv("QUERY_STRING"), "item"); char *userId = getenv("SI_UID"); if(userId == NULL) { InvalidRequest("405", "Incorrect configuration, no user id"); goto done; } else { MarkThisCartActive(userId); } if(!strcmp(role, "RESPONDER")) { if(strcmp(method, "GET")) { InvalidRequest("405", "Only GET Method Allowed"); } else if(op == NULL || !strcmp(op, OP_DISPLAY_STORE)) { DisplayStore(scriptName, parent, userId, fcgiProcessId); } else if(!strcmp(op, OP_ADD_ITEM)) { AddItemToCart(scriptName, parent, userId, fcgiProcessId, item); } else if(!strcmp(op, OP_DISPLAY_CART)) { DisplayCart(scriptName, parent, userId, fcgiProcessId); } else if(!strcmp(op, OP_REMOVE_ITEM)) { RemoveItemFromCart(scriptName, parent, userId, fcgiProcessId, item); } else if(!strcmp(op, OP_PURCHASE)) { Purchase(scriptName, parent, userId, fcgiProcessId); } else { InvalidRequest("404", "Invalid 'op' argument"); } } else if(!strcmp(role, "AUTHORIZER")) { Authorize(userId); } else { InvalidRequest("404", "Invalid FastCGI Role"); } done: Free(scriptName); Free(op); Free(item); } /* * Tiny database of shop inventory. The first form is the * item identifier used in a request, the second form is used * for HTML display. REQUIRED_ITEM is the item required * the the Authorizer. SPECIAL_ITEM is the item on the protected * page (must follow unprotected items in table). */ char *ItemNames[] = { "BrooklynBridge", "RMSTitanic", "CometKohoutec", "YellowSubmarine", NULL }; char *ItemDisplayNames[] = { "Brooklyn Bridge", "RMS Titanic", "Comet Kohoutec", "Yellow Submarine", NULL }; #define REQUIRED_ITEM 1 #define SPECIAL_ITEM 3 static char *ItemDisplayName(char *item) { int i; if(item == NULL) { return NULL; } for(i = 0; ItemNames[i] != NULL; i++) { if(!strcmp(item, ItemNames[i])) { return ItemDisplayNames[i]; } } return NULL; } static void DisplayNumberOfItems(int numberOfItems, char *processId); static void DisplayHead(char *title, char *parent, char *gif) { printf("Content-type: text/html\r\n" "\r\n" "\n\n%s\n\n\n" "\n", title); if(parent != NULL && gif != NULL) { printf("
\n\"[%s]\"\n
\n\n", parent, gif, title); } else { printf("

%s

\n
\n\n", title); } } static void DisplayFoot(void) { printf("
\n\n\n"); } static void DisplayStore( char *scriptName, char *parent, char *userId, char *processId) { Tcl_HashEntry *cartEntry = GetCartEntry(userId); ListOfString *items = ((CartObj *) Tcl_GetHashValue(cartEntry))->items; int numberOfItems = ListOfString_Length(items); int i; DisplayHead("FastCGI Shop!", parent, "Images/main-hd.gif"); DisplayNumberOfItems(numberOfItems, processId); printf("

Goods for sale:

\n
    \n"); for(i = 0; i < SPECIAL_ITEM; i++) { printf("
  • Add the %s\n" " to your shopping cart.\n", scriptName, ItemNames[i], ItemDisplayNames[i]); } printf("

\n\n"); printf("If the %s is in your shopping cart,\n" "go see a special offer\n" "available only to %s purchasers.

\n\n", ItemDisplayNames[REQUIRED_ITEM], parent, ItemNames[REQUIRED_ITEM], ItemDisplayNames[REQUIRED_ITEM]); printf("Purchase\n" "the contents of your shopping cart.

\n\n", parent); printf("View the contents\n" "of your shopping cart.

\n\n", scriptName); DisplayFoot(); } static Tcl_HashEntry *GetCartEntry(char *userId) { Tcl_HashEntry *cartEntry = Tcl_FindHashEntry(cartTablePtr, userId); int new; if(cartEntry == NULL) { CartObj *cart = Malloc(sizeof(CartObj)); cart->inactive = FALSE; cart->items = NULL; cartEntry = Tcl_CreateHashEntry(cartTablePtr, userId, &new); assert(new); Tcl_SetHashValue(cartEntry, cart); } return cartEntry; } static void AddItemToCart( char *scriptName, char *parent, char *userId, char *processId, char *item) { if(DoAddItemToCart(userId, item, TRUE) < 0) { InvalidRequest("404", "Invalid 'item' argument"); } else { /* * Would call * DisplayStore(scriptName, parent, userId, processId); * except for browser reload issue. Redirect instead. */ printf("Location: %s?op=%s\r\n" "\r\n", scriptName, OP_DISPLAY_STORE); } } static int DoAddItemToCart(char *userId, char *item, int writeLog) { if(ItemDisplayName(item) == NULL) { return -1; } else { Tcl_HashEntry *cartEntry = GetCartEntry(userId); CartObj *cart = Tcl_GetHashValue(cartEntry); cart->items = ListOfString_AppendElement( cart->items, StringCopy(item)); if(writeLog) { WriteLog(LR_ADD_ITEM, userId, item, TRUE); } } return 0; } static void DisplayCart( char *scriptName, char *parent, char *userId, char *processId) { Tcl_HashEntry *cartEntry = GetCartEntry(userId); CartObj *cart = Tcl_GetHashValue(cartEntry); ListOfString *items = cart->items; int numberOfItems = ListOfString_Length(items); DisplayHead("Your shopping cart", parent, "Images/cart-hd.gif"); DisplayNumberOfItems(numberOfItems, processId); printf("

    \n"); for(; items != NULL; items = ListOfString_Tail(items)) { char *item = ListOfString_Head(items); printf("
  • %s . . . . . \n" " Click\n" " to remove from your shopping cart.\n", ItemDisplayName(item), scriptName, item); } printf("

\n\n"); printf("Purchase\n" "the contents of your shopping cart.

\n\n", parent); printf("Return to shop.

\n\n", scriptName); DisplayFoot(); } static void RemoveItemFromCart( char *scriptName, char *parent, char *userId, char *processId, char *item) { if(DoRemoveItemFromCart(userId, item, TRUE) < 0) { InvalidRequest("404", "Invalid 'item' argument"); } else { /* * Would call * DisplayCart(scriptName, parent, userId, processId); * except for browser reload issue. Redirect instead. */ printf("Location: %s?op=%s\r\n" "\r\n", scriptName, OP_DISPLAY_CART); } } static int DoRemoveItemFromCart(char *userId, char *item, int writeLog) { if(ItemDisplayName(item) == NULL) { return -1; } else { Tcl_HashEntry *cartEntry = GetCartEntry(userId); CartObj *cart = Tcl_GetHashValue(cartEntry); if(ListOfString_IsElement(cart->items, item)) { cart->items = ListOfString_RemoveElement(cart->items, item); if (writeLog) { WriteLog(LR_REMOVE_ITEM, userId, item, TRUE); } } } return 0; } static void Purchase( char *scriptName, char *parent, char *userId, char *processId) { DoEmptyCart(userId, TRUE); printf("Location: %sUnprotected/ThankYou.html\r\n" "\r\n", parent); } static int DoEmptyCart(char *userId, int writeLog) { Tcl_HashEntry *cartEntry = GetCartEntry(userId); CartObj *cart = Tcl_GetHashValue(cartEntry); ListOfString *items = cart->items; /* * Write log *before* tearing down cart structure because userId * is part of the structure. (Thanks, Purify.) */ if (writeLog) { WriteLog(LR_EMPTY_CART, userId, "NullItem", TRUE); } while(items != NULL) { items = ListOfString_RemoveElement( items, ListOfString_Head(items)); } Free(cart); Tcl_DeleteHashEntry(cartEntry); return 0; } static void NotAuthorized(void); static void Authorize(char *userId) { Tcl_HashEntry *cartEntry = GetCartEntry(userId); ListOfString *items = ((CartObj *) Tcl_GetHashValue(cartEntry))->items; for( ; items != NULL; items = ListOfString_Tail(items)) { if(!strcmp(ListOfString_Head(items), ItemNames[REQUIRED_ITEM])) { printf("Status: 200 OK\r\n" "Variable-Foo: Bar\r\n" "\r\n"); return; } } NotAuthorized(); } static void DisplayNumberOfItems(int numberOfItems, char *processId) { if(processId != NULL) { printf("FastCGI process %s is serving you today.
\n", processId); } if(numberOfItems == 0) { printf("Your shopping cart is empty.

\n\n"); } else if(numberOfItems == 1) { printf("Your shopping cart contains 1 item.

\n\n"); } else { printf("Your shopping cart contains %d items.

\n\n", numberOfItems); }; } static void InvalidRequest(char *code, char *message) { printf("Status: %s %s\r\n", code, message); DisplayHead("Invalid request", NULL, NULL); printf("%s.\n\n", message); DisplayFoot(); } static void NotAuthorized(void) { printf("Status: 403 Forbidden\r\n"); DisplayHead("Access Denied", NULL, NULL); printf("Put the %s in your cart to access this page.\n\n", ItemDisplayNames[REQUIRED_ITEM]); DisplayFoot(); } /* * Mundane utility functions, not specific to this application: */ /* * Fail-fast version of 'malloc' */ static void *Malloc(size_t size) { void *result = malloc(size); assert(size == 0 || result != NULL); return result; } /* * Protect against old, broken implementations of 'free' */ static void Free(void *ptr) { if(ptr != NULL) { free(ptr); } } /* * Return a new string created by calling Malloc, copying strLen * characters from str to the new string, then appending a null. */ static char *StringNCopy(char *str, int strLen) { char *newString = Malloc(strLen + 1); memcpy(newString, str, strLen); newString[strLen] = '\000'; return newString; } /* * Return a new string that's a copy of str, including the null */ static char *StringCopy(char *str) { return StringNCopy(str, strlen(str)); } /* * Return a new string that's a copy of str1 followed by str2, * including the null */ static char *StringCat(char *str1, char *str2) { return StringCat4(str1, str2, NULL, NULL); } static char *StringCat4(char *str1, char *str2, char *str3, char *str4) { int str1Len = Strlen(str1); int str2Len = Strlen(str2); int str3Len = Strlen(str3); int str4Len = Strlen(str4); char *newString = Malloc(str1Len + str2Len + str3Len + str4Len + 1); memcpy(newString, str1, str1Len); memcpy(newString + str1Len, str2, str2Len); memcpy(newString + str1Len + str2Len, str3, str3Len); memcpy(newString + str1Len + str2Len + str3Len, str4, str4Len); newString[str1Len + str2Len + str3Len + str4Len] = '\000'; return newString; } /* * Return a copy of the value associated with 'name' in 'query'. * XXX: does not perform URL-decoding of query. */ static char *QueryLookup(char *query, char *name) { int nameLen = strlen(name); char *queryTail, *nameFirst, *valueFirst, *valueLast; if(query == NULL) { return NULL; } queryTail = query; for(;;) { nameFirst = strstr(queryTail, name); if(nameFirst == NULL) { return NULL; } if(((nameFirst == query) || (nameFirst[-1] == '&')) && (nameFirst[nameLen] == '=')) { valueFirst = nameFirst + nameLen + 1; valueLast = strchr(valueFirst, '&'); if(valueLast == NULL) { valueLast = strchr(valueFirst, '\000'); }; return StringNCopy(valueFirst, valueLast - valueFirst); } queryTail = nameFirst + 1; } } /* * Return a copy of the characters following the final '/' character * of path. */ static char *PathTail(char *path) { char *afterSlash, *slash; if(path == NULL) { return NULL; } afterSlash = path; while((slash = strchr(afterSlash, '/')) != NULL) { afterSlash = slash + 1; } return StringCopy(afterSlash); } /* * Return the integer value of the specified environment variable, * or a specified default value if the variable is unbound. */ static int IntGetEnv(char *varName, int defaultValue) { char *strValue = getenv(varName); int value = 0; if(strValue != NULL) { value = strtol(strValue, NULL, 10); } if(value <= 0) { value = defaultValue; } return value; } /* * Should the Tcl hash package detect an unrecoverable error(!), halt. */ void panic(char *format, char *arg1, char *arg2, char *arg3, char *arg4, char *arg5, char *arg6, char *arg7, char *arg8) { assert(FALSE); } /* * ListOfString abstraction */ static char *ListOfString_Head(ListOfString *list) { return list->head; } static ListOfString *ListOfString_Tail(ListOfString *list) { return list->tail; } static int ListOfString_Length(ListOfString *list) { int length = 0; for(; list != NULL; list = list->tail) { length++; } return length; } static int ListOfString_IsElement(ListOfString *list, char *element) { for(; list != NULL; list = list->tail) { if(!strcmp(list->head, element)) { return TRUE; } } return FALSE; } static ListOfString *ListOfString_AppendElement( ListOfString *list, char *element) { ListOfString *cur; ListOfString *newCell = Malloc(sizeof(ListOfString)); newCell->head = element; newCell->tail = NULL; if(list == NULL) { return newCell; } else { for(cur = list; cur->tail != NULL; cur = cur->tail) { } cur->tail = newCell; return list; } } static ListOfString *ListOfString_RemoveElement( ListOfString *list, char *element) { ListOfString *cur; ListOfString *prevCell = NULL; for(cur = list; cur != NULL; cur = cur->tail) { if(!strcmp(cur->head, element)) { if(prevCell == NULL) { list = cur->tail; } else { prevCell->tail = cur->tail; } free(cur->head); free(cur); return list; } prevCell = cur; } return list; } /* * End */