tool/srcck1.c

   1 /*
   2 ** The program does some simple static analysis of the sqlite3.c source
   3 ** file looking for mistakes.
   4 **
   5 ** Usage:
   6 **
   7 **      ./srcck1 sqlite3.c
   8 **
   9 ** This program looks for instances of assert(), ALWAYS(), NEVER() or
  10 ** testcase() that contain side-effects and reports errors if any such
  11 ** instances are found.
  12 **
  13 ** The aim of this utility is to prevent recurrences of errors such
  14 ** as the one fixed at:
  15 **
  16 **   https://www.sqlite.org/src/info/a2952231ac7abe16
  17 **
  18 ** Note that another similar error was found by this utility when it was
  19 ** first written.  That other error was fixed by the same check-in that
  20 ** committed the first version of this utility program.
  21 */
  22 #include <stdlib.h>
  23 #include <ctype.h>
  24 #include <stdio.h>
  25 #include <string.h>
  26
  27 /* Read the complete text of a file into memory.  Return a pointer to
  28 ** the result.  Panic if unable to read the file or allocate memory.
  29 */
  30 static char *readFile(const char *zFilename){
  31   FILE *in;
  32   char *z;
  33   long n;
  34   size_t got;
  35
  36   in = fopen(zFilename, "rb");
  37   if( in==0 ){
  38     fprintf(stderr, "unable to open '%s' for reading\n", zFilename);
  39     exit(1);
  40   }
  41   fseek(in, 0, SEEK_END);
  42   n = ftell(in);
  43   rewind(in);
  44   z = malloc( n+1 );
  45   if( z==0 ){
  46     fprintf(stderr, "cannot allocate %d bytes to store '%s'\n",
  47             (int)(n+1), zFilename);
  48     exit(1);
  49   }
  50   got = fread(z, 1, n, in);
  51   fclose(in);
  52   if( got!=(size_t)n ){
  53     fprintf(stderr, "only read %d of %d bytes from '%s'\n",
  54            (int)got, (int)n, zFilename);
  55     exit(1);
  56   }
  57   z[n] = 0;
  58   return z;
  59 }
  60
  61 /* Check the C code in the argument to see if it might have
  62 ** side effects.  The only accurate way to know this is to do a full
  63 ** parse of the C code, which this routine does not do.  This routine
  64 ** uses a simple heuristic of looking for:
  65 **
  66 **    *  '=' not immediately after '>', '<', '!', or '='.
  67 **    *  '++'
  68 **    *  '--'
  69 **
  70 ** If the code contains the phrase "side-effects-ok" is inside a
  71 ** comment, then always return false.  This is used to disable checking
  72 ** for assert()s with deliberate side-effects, such as used by
  73 ** SQLITE_TESTCTRL_ASSERT - a facility that allows applications to
  74 ** determine at runtime whether or not assert()s are enabled.
  75 ** Obviously, that determination cannot be made unless the assert()
  76 ** has some side-effect.
  77 **
  78 ** Return true if a side effect is seen.  Return false if not.
  79 */
  80 static int hasSideEffect(const char *z, unsigned int n){
  81   unsigned int i;
  82   for(i=0; i<n; i++){
  83     if( z[i]=='/' && strncmp(&z[i], "/*side-effects-ok*/", 19)==0 ) return 0;
  84     if( z[i]=='=' && i>0 && z[i-1]!='=' && z[i-1]!='>'
  85            && z[i-1]!='<' && z[i-1]!='!' && z[i+1]!='=' ) return 1;
  86     if( z[i]=='+' && z[i+1]=='+' ) return 1;
  87     if( z[i]=='-' && z[i+1]=='-' ) return 1;
  88   }
  89   return 0;
  90 }
  91
  92 /* Return the number of bytes in string z[] prior to the first unmatched ')'
  93 ** character.
  94 */
  95 static unsigned int findCloseParen(const char *z){
  96   unsigned int nOpen = 0;
  97   unsigned i;
  98   for(i=0; z[i]; i++){
  99     if( z[i]=='(' ) nOpen++;
 100     if( z[i]==')' ){
 101       if( nOpen==0 ) break;
 102       nOpen--;
 103     }
 104   }
 105   return i;
 106 }
 107
 108 /* Search for instances of assert(...), ALWAYS(...), NEVER(...), and/or
 109 ** testcase(...) where the argument contains side effects.
 110 **
 111 ** Print error messages whenever a side effect is found.  Return the number
 112 ** of problems seen.
 113 */
 114 static unsigned int findAllSideEffects(const char *z){
 115   unsigned int lineno = 1;   /* Line number */
 116   unsigned int i;
 117   unsigned int nErr = 0;
 118   char c, prevC = 0;
 119   for(i=0; (c = z[i])!=0; prevC=c, i++){
 120     if( c=='\n' ){ lineno++; continue; }
 121     if( isalpha(c) && !isalpha(prevC) ){
 122       if( strncmp(&z[i],"assert(",7)==0
 123        || strncmp(&z[i],"ALWAYS(",7)==0
 124        || strncmp(&z[i],"NEVER(",6)==0
 125        || strncmp(&z[i],"testcase(",9)==0
 126       ){
 127         unsigned int n;
 128         const char *z2 = &z[i+5];
 129         while( z2[0]!='(' ){ z2++; }
 130         z2++;
 131         n = findCloseParen(z2);
 132         if( hasSideEffect(z2, n) ){
 133           nErr++;
 134           fprintf(stderr, "side-effect line %u: %.*s\n", lineno,
 135                   (int)(&z2[n+1] - &z[i]), &z[i]);
 136         }
 137       }
 138     }
 139   }
 140   return nErr;
 141 }
 142
 143 int main(int argc, char **argv){
 144   char *z;
 145   unsigned int nErr = 0;
 146   if( argc!=2 ){
 147     fprintf(stderr, "Usage: %s FILENAME\n", argv[0]);
 148     return 1;
 149   }
 150   z = readFile(argv[1]);
 151   nErr = findAllSideEffects(z);
 152   free(z);
 153   if( nErr ){
 154     fprintf(stderr, "Found %u undesirable side-effects\n", nErr);
 155     return 1;
 156   }
 157   return 0;
 158 }