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#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
bool try_complete_pread(int fd, void *ptr, size_t len, off_t offset)
{
while (len > 0) {
ssize_t ret = pread(fd, ptr, len, offset);
if (ret == -1 && errno == EINTR) {
continue;
}
if (ret == 0) {
errno = 0;
return false;
}
if (ret <= 0) {
return false;
}
ptr = reinterpret_cast<char *>(ptr) + ret;
len -= ret;
offset += ret;
}
return true;
}
void complete_pread(int fd, void *ptr, size_t len, off_t offset, const char *filename_for_errors)
{
if (!try_complete_pread(fd, ptr, len, offset)) {
if (errno == 0) {
fprintf(stderr, "%s: Short read (file corrupted?)\n", filename_for_errors);
} else {
perror(filename_for_errors);
}
exit(1);
}
}
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