yann@1492: #include <limits.h>
yann@1492: #include <stdlib.h>
yann@1492: #include <stdio.h>
yann@1492: #include <string.h>
yann@1492: #include <sys/types.h>
yann@1492: #include <sys/stat.h>
yann@1492: #include <unistd.h>
yann@1492: #include <errno.h>
yann@1492: 
yann@1492: 
yann@1492: /* Needed for execve */
yann@1492: extern char **environ;
yann@1492: 
yann@1492: int main( int argc,
yann@1492:           char** argv )
yann@1492: {
yann@1492:   char *fullname;   /* 'fullname' is used to store the absolute path to the
yann@1492:                        tool being executed; it serves as a base to compute
yann@1492:                        the realname of that tool, and the directory holding
yann@1492:                        our runtime libraries */
yann@1492:   char *realname;   /* 'realname' is the real name of the tool, that is what
yann@1492:                        the wrapper is currently impersonating */
yann@1492:   char *basedir;    /* 'libdir' contains our runtime libraries */
yann@1492: 
yann@1492:   char *lastslash;  /* Temporary variables now */
yann@1492:   char *ldlibpath;
yann@1492:   size_t len;
yann@1492:   int execve_ret;
yann@1492: 
yann@1492:   /* In case we have a relative or absolute pathname (ie. contains a slash),
yann@1492:    * then realpath wll work. But if the tool was found in the PATH, realpath
yann@1492:    * won't work, and we'll have to search ourselves.
yann@1492:    * This if{}else{} block allocates memory for fullname. */
yann@1492:   if( strchr( argv[0], '/' ) ) {
yann@1492:     fullname = (char*) malloc( PATH_MAX * sizeof(char) );
yann@1492:     if( ! realpath( argv[0], fullname ) ) {
yann@1492:       perror( "tool wrapper" );
yann@1492:       exit( 1 );
yann@1492:     }
yann@1492:   } else {
yann@1492:     char *path;
yann@1492:     char *mypath;
yann@1492:     char *colon;
yann@1492:     char *testname;
yann@1492:     struct stat st;
yann@1492: 
yann@1492:     fullname = NULL;
yann@1492:     colon = mypath = path = strdup( getenv( "PATH" ) );
yann@1492:     while( colon ) {
yann@1492:       colon = strchr( mypath, ':' );
yann@1492:       if( colon ) {
yann@1492:         *colon = '\0';
yann@1492:       }
yann@1492:       testname = strdup( mypath );
yann@1492:       testname = (char*) realloc( testname,   strlen( testname )
yann@1492:                                             + strlen( argv[0] )
yann@1492:                                             + 2 * sizeof(char) );
yann@1492:       memset( testname + strlen( testname ),
yann@1492:               0,
yann@1492:               strlen( argv[0] ) + 2 * sizeof(char) );
yann@1492:       strcat( testname, "/" );
yann@1492:       strcat( testname, argv[0] );
yann@1492:       if( stat( testname, &st ) == 0 ) {
yann@1492:         /* OK, exists. Is it a regular file, or a
yann@1492:          * symlink, which the current user may execute? */
yann@1492:         if( S_ISREG( st.st_mode ) && ! access( testname, X_OK || R_OK ) ) {
yann@1492:           fullname = strdup( testname );
yann@1492:           break;
yann@1492:         }
yann@1492:       }
yann@1492:       free( testname );
yann@1492:       mypath = colon + 1;
yann@1492:     }
yann@1492:     free( path );
yann@1492:     if( ! fullname ) {
yann@1492:       fprintf( stderr, "tool wrapper: %s: command not found\n", argv[0] );
yann@1492:       exit( 1 );
yann@1492:     }
yann@1492:   }
yann@1492: 
yann@1492:   /* Duplicate my own name to add the 'dot' to tool name */
yann@1492:   realname = strdup( fullname );
yann@1492:   realname = (char*) realloc( realname, strlen( realname) + 2 * sizeof(char) );
yann@1492:   realname[ strlen( realname ) + 1 ] = '\0';
yann@1492: 
yann@1492:   /* Add the dot after the last '/' */
yann@1492:   lastslash = strrchr( realname, '/' );
yann@1492:   memmove( lastslash + 1, lastslash, strlen( lastslash ) );
yann@1492:   *( lastslash + 1 ) = '.';
yann@1492: 
yann@1492:   /* Compute the basedir of the tool */
yann@1492:   basedir = strdup( fullname );
yann@1492:   lastslash = strrchr( basedir, '/' );
yann@1492:   *lastslash = '\0';
yann@1492:   lastslash = strrchr( basedir, '/' );
yann@1492:   *lastslash = '\0';
yann@1492: 
yann@1492:   /* Append '/lib' */
yann@1492:   len = strlen( basedir );
yann@1492:   basedir = (char*) realloc( basedir, len + 5 );
yann@1492:   *( basedir + len ) = '\0';
yann@1492:   strcat( basedir, "/lib" );
yann@1492: 
yann@1492:   /* Now add the directory with our runtime libraries to the
yann@1492:      front of the library search path, LD_LIBRARY_PATH */
yann@1492:   ldlibpath = getenv( "LD_LIBRARY_PATH" );
yann@1492:   if( ldlibpath ) {
yann@1492:     basedir = (char*) realloc( basedir,   strlen( basedir )
yann@1492:                                         + strlen( ldlibpath )
yann@1492:                                         + 2 * sizeof(char) );
yann@1492:     strcat( basedir, ":" );
yann@1492:     strcat( basedir, ldlibpath );
yann@1492:   }
yann@1492: 
yann@1492:   if( setenv( "LD_LIBRARY_PATH", basedir, 1 ) ) {
yann@1492:     errno = ENOMEM;
yann@1492:     perror( "tool wrapper" );
yann@1492:     exit( 1 );
yann@1492:   }
yann@1492: 
yann@1492:   /* Execute the real tool, now */
yann@1492:   execve_ret = execve( realname, argv, environ );
yann@1492: 
yann@1492:   /* In case something went wrong above, print a
yann@1492:      diagnostic message, and exit with error code 1 */
yann@1492:   perror( "tool wrapper" );
yann@1492:   return 1;
yann@1492: }