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/*
* fread.c
*/
#include <stdbool.h>
#include <string.h>
#include "stdioint.h"
size_t _fread(void *buf, size_t count, FILE *file)
{
struct _IO_file_pvt *f = stdio_pvt(file);
size_t bytes = 0;
size_t nb;
char *p = buf;
char *rdptr;
ssize_t rv;
bool bypass;
if (!count)
return 0;
if (f->obytes) /* User error! */
__fflush(f);
while (count) {
while (f->ibytes == 0) {
/*
* The buffer is empty, we have to read
*/
bypass = (count >= f->bufsiz);
if (bypass) {
/* Large read, bypass buffer */
rdptr = p;
nb = count;
} else {
rdptr = f->buf + _IO_UNGET_SLOP;
nb = f->bufsiz;
}
rv = read(f->pub._IO_fileno, rdptr, nb);
if (rv == -1) {
if (errno == EINTR || errno == EAGAIN)
continue;
f->pub._IO_error = true;
return bytes;
} else if (rv == 0) {
f->pub._IO_eof = true;
return bytes;
}
if (bypass) {
p += rv;
bytes += rv;
count -= rv;
} else {
f->ibytes = rv;
f->data = rdptr;
}
if (!count)
return bytes;
}
/* If we get here, the buffer is non-empty */
nb = f->ibytes;
nb = (count < nb) ? count : nb;
if (nb) {
memcpy(p, f->data, nb);
p += nb;
bytes += nb;
count -= nb;
f->data += nb;
f->ibytes -= nb;
}
}
return bytes;
}
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