Steven, Bruno, Attached please find a patch and demo program for a new function mr_stresc() to properly escape strings for use as arguments with (the likes of) system() and popen().
I have thought about using functions like exec() or fork() to avoid system() and popen(). I don't really see how the two latter would be generally evil. To the contrary, e.g. using a function that submits things to 'sh -c' means we have a sane environment like a PATH and so forth. Also, look at the sheer number of occurrences of system() and popen()! (Mind you, I am not saying that nothing should be converted to use exec() or fork(), only that I believe there will and should always be some calls to system() and open().) I therefore suggest use of the attached function when calling system() or popen() where required. I believe this is low-risk, low-overhead, little work, a clean approach and can be done bit by bit. What do you say? Apart from this, the function itself may be buggy or not do what it should. I've tested it and it works for me, but it would be very good if you, Steven, could apply attached patch and run mondoarchive again to test. Also, general feedback on the actual code would be highly welcome. Best regards, Andree -- Andree Leidenfrost @ Debian Developer Sydney - Australia
mondo_bts#379966.diff
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#include <stdlib.h>
#include <string.h>
#include <stdio.h>
char *mr_stresc(const char *inptr, const char *toesc, const char escchr) {
char *retstr = NULL;
char *retptr = NULL;
char *escptr = NULL;
retstr = (char *)malloc(strlen(inptr) + strspn(inptr, toesc) + 1);
retptr = (char *)retstr;
while (*inptr != '\0') {
escptr = (char *)toesc;
while (*escptr != '\0') {
if (*inptr == *escptr++) {
*retptr++ = escchr;
break;
}
}
*retptr++ = *inptr++;
}
*retptr = '\0';
return retstr;
}
int main() {
const char escchr = '\\';
const char escape_list[3] = "`$\\";
char string[44] = "These need escaping: `$\\, these don't: abc.";
printf("Before: %s\n", string);
printf("After: %s\n", mr_stresc(string, escape_list, escchr));
return 0;
}
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