Visual Studio error LNK2001: unresolved external symbol _fgetc_unlocked

Question

I'm trying to use libjasper from http://www.ece.uvic.ca/~frodo/jasper/ as a static library in compiling dcraw.c from http://www.cybercom.net/~dcoffin/dcraw/ on windows with VC9. I have resolved several issues on the way and finally get three linking errors.

1>dcraw.obj : error LNK2001: unresolved external symbol _ftello
1>dcraw.obj : error LNK2001: unresolved external symbol _fseeko
1>dcraw.obj : error LNK2001: unresolved external symbol _getc_unlocked

the first two of these are easily resolved it seems, I added

#define fseeko _fseeki64
#define ftello _ftelli64

and that does it but what about the third one:

1>dcraw.obj : error LNK2001: unresolved external symbol _getc_unlocked

How can I work around that on windows with visual studio?

Thanks.

Answer 1

The actual equivalent of getc_unlocked is not getc , it's _fgetc_nolock . So, assuming that whoever wrote the original code knew what he's doing and had some reasons to prefer the thread-unsafe version, you probably want this :

#define getc_unlocked _fgetc_nolock

Answer 2

#define getc_unlocked _fgetc_nolock

Only difference is that getc is thread-safe (and probably slower).

http://pubs.opengroup.org/onlinepubs/000095399/functions/getc_unlocked.html

EDIT: As @Fanael pointed out in another answer, _fgetc_nolock makes for a better replacement than getc .

Answer 3

这是一个不在win32上的posix函数，只是这样做

#define getc_unlocked fgetc

Answer 4

Replace calls to getc and getc_unlocked with fgetc when compiling for Windows.

I vaguely remember ftello, fseeko and possibly getc_unlocked as being specific to linux/gcc/posix.

getc is roughly prototyped as int getc( FILE* f);

fgetc is roughly prototyped as int fgetc( FILE* f );

and, in fact, in MSVS 10, getc is a define for fgetc.