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#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
/* * * * * * * Routines to parse a line into an array of tokens * * * * * * */
static int istoken(c, tokens)
char c;
char *tokens;
{
while ( *tokens ) {
if ( c == *(tokens++) )
return(1);
}
return(0);
}
/* This version of tokenize is destructive to the line it parses. */
void tokenize(array, line, tokens)
char *array[];
char *line;
char *tokens;
{
char *head, *ptr;
int i=0;
for ( head=line; *line; ) {
if ( istoken(*line, tokens) ) {
*(line++)='\0';
array[i++]=head;
while ( istoken(*line, tokens) )
++line;
head=line;
} else
++line;
}
array[i++]=head;
array[i]=NULL;
}
/* Return the pathname of the command, or NULL if it's not in our PATH */
/* Warning: We use a static buffer that is overwritten at each invocation. */
char *pathsearch(command, secure)
char *command;
int secure;
{
#ifndef S_IFREG
#define S_IFREG 0100000
#endif
char *path, *newpath, *paths[256];
static char buffer[1024];
int i;
struct stat sb;
if ( (path=(char *)getenv("PATH")) == NULL )
return(NULL);
if ( (newpath=(char *)malloc(strlen(path)+1)) == NULL )
return(NULL);
strcpy(newpath, path);
tokenize(paths, newpath, ":");
for ( i=0; paths[i]; ++i ) {
if ( secure && paths[i][0] != '/' ) {
/* Only allow full pathnames */
continue;
}
/* Make sure the file exists */
sprintf(buffer, "%s/%s", paths[i], command);
if ( stat(buffer, &sb) != 0 )
continue;
/* Make sure it's a regular file */
if ( (sb.st_mode & S_IFREG) != S_IFREG )
continue;
/* Now make sure we can execute it */
if ( sb.st_uid == getuid() ) {
/* User execute permission? */
if ( sb.st_mode & 0100 )
break;
} else if ( sb.st_gid == getgid() ) {
/* Group execute permission? */
if ( sb.st_mode & 0010 )
break;
} else {
/* Other execute permission? */
if ( sb.st_mode & 0001 )
break;
}
}
(void) free(newpath);
if ( paths[i] == NULL )
return(NULL);
else
return(buffer);
}
main(argc, argv)
int argc;
char *argv[];
{
char *path;
if ( argc != 2 ) {
fprintf(stderr, "Usage: %s command\n", argv[0]);
exit(1);
}
if ( (path=pathsearch(argv[1], 0)) )
printf("%s\n", path);
exit(0);
}
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