scratching my head over a c problem...

today, i wanted to try out my test arabic gtk program to see if behdad’s new changes to pango magically fixed the renown arabic shaping issue [in short, it had nothing to do with it]. anyway, i discovered that i needed to install libquran, and to make a long story short, my test program, which used to work before, segfaulted. i ran gdb and valgrind only to find the segfault happening within libquran at the closing of the configuration file (noting this libquran code hasn’t been changed in 3 years now).

i looked at the source, and discovered that the file pointer was becoming null after a call to getline. i tried to see if i could reproduce this in a smaller test program, and i discovered that i indeed could -

#include <stdio.h>

int main(void){
   int n = 0;
   char* tmp;
   FILE* fp = fopen("./testfile", "r");
   getline(&tmp, &n, fp);
   printf("got a str of: %s\n", tmp);
   printf("now fp is: %s\n", (fp==NULL)? "null" : "not null");
   return 0;

the program displayed the first line from testfile, but unexpectedly displayed that fp is null and segfaulted at the fclose. checking the return from getline, i see that it returns successfully (the number of characters it read).

while i got around this problem by modifying the library to do a malloc followed by an fgets, i am just confused -this library code hasn’t been touched in 3 years, it used to work before, and i just repulled it from cvs when i discovered this. so why is it broken now? the only thing that i can think of being different is that my box now runs a 64 bit version of linux, but would that break it?

any ideas?

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