c - Using fseek and ftell to determine the size of a file has a vulnerability? -

i've read posts show how use fseek , ftell determine size of file.

file *fp; long file_size; char *buffer;  fp = fopen("foo.bin", "r"); if (null == fp) {  /* handle error */ }  if (fseek(fp, 0 , seek_end) != 0) {   /* handle error */ }  file_size = ftell(fp); buffer = (char*)malloc(file_size); if (null == buffer){   /* handle error */ } 

i use technique ran link describes potential vulnerability.

the link recommends using fstat instead. can comment on this?

the link 1 of many nonsensical pieces of c coding advice cert. justification based on liberties c standard allows implementation take, not allowed posix , irrelevant in cases have fstat alternative.

posix requires:

1. that "b" modifier fopen have no effect, i.e. text , binary mode behave identically. means concern invoking ub on text files nonsense.

2. that files have byte-resolution size set write operations , truncate operations. means concern random numbers of null bytes @ end of file nonsense.

sadly nonsense publish, it's hard know cert publications take seriously. shame, because lots of them serious.