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23 January 2022, 05:21:09 UTC
Revision 3b97fee23df7ec78eea77151fcc0885ec3191950 authored by Eric Wong on 11 January 2007, 21:43:40 UTC, committed by Junio C Hamano on 11 January 2007, 22:49:45 UTC 
Avoid errors and warnings when attempting to do I/O on zero bytes
 
Unfortunately, while {read,write}_in_full do take into account
zero-sized reads/writes; their die and whine variants do not.

I have a repository where there are zero-sized files in
the history that was triggering these things.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>
1 parent 9130ac1
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Tip revision: 3b97fee23df7ec78eea77151fcc0885ec3191950 authored by Eric Wong on 11 January 2007, 21:43:40 UTC
Avoid errors and warnings when attempting to do I/O on zero bytes
Tip revision: 3b97fee
write_or_die.c 
#include "cache.h"

int read_in_full(int fd, void *buf, size_t count)
{
	char *p = buf;
	ssize_t total = 0;
	ssize_t loaded = 0;

	while (count > 0) {
		loaded = xread(fd, p, count);
		if (loaded <= 0) {
			if (total)
				return total;
			else
				return loaded;
		}
		count -= loaded;
		p += loaded;
		total += loaded;
	}

	return total;
}

void read_or_die(int fd, void *buf, size_t count)
{
	ssize_t loaded;

	if (!count)
		return;
	loaded = read_in_full(fd, buf, count);
	if (loaded == 0)
		die("unexpected end of file");
	else if (loaded < 0)
		die("read error (%s)", strerror(errno));
}

int write_in_full(int fd, const void *buf, size_t count)
{
	const char *p = buf;
	ssize_t total = 0;

	while (count > 0) {
		size_t written = xwrite(fd, p, count);
		if (written < 0)
			return -1;
		if (!written) {
			errno = ENOSPC;
			return -1;
		}
		count -= written;
		p += written;
		total += written;
	}

	return total;
}

void write_or_die(int fd, const void *buf, size_t count)
{
	ssize_t written;

	if (!count)
		return;
	written = write_in_full(fd, buf, count);
	if (written == 0)
		die("disk full?");
	else if (written < 0) {
		if (errno == EPIPE)
			exit(0);
		die("write error (%s)", strerror(errno));
	}
}

int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg)
{
	ssize_t written;

	if (!count)
		return 1;
	written = write_in_full(fd, buf, count);
	if (written == 0) {
		fprintf(stderr, "%s: disk full?\n", msg);
		return 0;
	}
	else if (written < 0) {
		if (errno == EPIPE)
			exit(0);
		fprintf(stderr, "%s: write error (%s)\n",
			msg, strerror(errno));
		return 0;
	}

	return 1;
}

int write_or_whine(int fd, const void *buf, size_t count, const char *msg)
{
	ssize_t written;

	if (!count)
		return 1;
	written = write_in_full(fd, buf, count);
	if (written == 0) {
		fprintf(stderr, "%s: disk full?\n", msg);
		return 0;
	}
	else if (written < 0) {
		fprintf(stderr, "%s: write error (%s)\n",
			msg, strerror(errno));
		return 0;
	}

	return 1;
}
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