Comment 0 for bug 1961954

Hot to reproduce :

$ strfile fort
"fort.dat" created
There were 36 strings
Longest string: 201 bytes
Shortest string: 25 bytes

$ ls -l fort*
-rw-rw-r-- 1 br br 3383 Feb 23 10:31 fort
-rw-rw-r-- 1 br br 172 Feb 23 10:31 fort.dat

$ unstr fort
Input file: fort
unstr: data file corrupted

The bug is line 234 of unstr.c (source file: https://sources.debian.org/src/fortune-mod/1%3A1.99.1-7/util/unstr.c/).

The current checked_fread() macro compares fread() return value with the number of bytes to read :
#define checked_fread(item, size) \
    if (fread(item, size, 1, Dataf) != size) \
      { \
        fprintf(stderr, "unstr: data file corrupted\n"); \
        exit(1); \
      }

It should instead compare fread() return value with the number of items to read, which is 1 :
#define checked_fread(item, size) \
    if (fread(item, size, 1, Dataf) != 1) \
      { \
        fprintf(stderr, "unstr: data file corrupted\n"); \
        exit(1); \
      }

After changing the code, running the same commands give :
$ strfile fort
"fort.dat" created
There were 36 strings
Longest string: 201 bytes
Shortest string: 25 bytes

$ ls -l fort*
-rw-rw-r-- 1 br br 3383 Feb 23 10:31 fort
-rw-rw-r-- 1 br br 172 Feb 23 10:38 fort.dat

$ ./unstr fort
Input file: fort
nothing to do -- table in file order