Rich Felker
400c5e5c83
to deal with the fact that the public headers may be used with pre-c99 compilers, __restrict is used in place of restrict, and defined appropriately for any supported compiler. we also avoid the form [restrict] since older versions of gcc rejected it due to a bug in the original c99 standard, and instead use the form *restrict.
47 lines
998 B
C
47 lines
998 B
C
#include "stdio_impl.h"
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/* The basic idea of this implementation is to open a new FILE,
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* hack the necessary parts of the new FILE into the old one, then
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* close the new FILE. */
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/* Locking is not necessary because, in the event of failure, the stream
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* passed to freopen is invalid as soon as freopen is called. */
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FILE *freopen(const char *restrict filename, const char *restrict mode, FILE *restrict f)
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{
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int fl;
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FILE *f2;
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fflush(f);
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if (!filename) {
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f2 = fopen("/dev/null", mode);
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if (!f2) goto fail;
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fl = syscall(SYS_fcntl, f2->fd, F_GETFL, 0);
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if (fl < 0 || syscall(SYS_fcntl, f->fd, F_SETFL, fl) < 0)
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goto fail2;
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} else {
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f2 = fopen(filename, mode);
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if (!f2) goto fail;
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if (syscall(SYS_dup2, f2->fd, f->fd) < 0)
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goto fail2;
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}
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f->flags = (f->flags & F_PERM) | f2->flags;
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f->read = f2->read;
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f->write = f2->write;
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f->seek = f2->seek;
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f->close = f2->close;
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fclose(f2);
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return f;
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fail2:
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fclose(f2);
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fail:
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fclose(f);
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return NULL;
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}
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LFS64(freopen);
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