Skip to main content

Browse the archive

Revision 3ebbd00cf3c5a7c6f90e2fed8adaf0c5145fb4ac authored by Jim Hill on 31 May 2015, 18:16:45 UTC, committed by Junio C Hamano on 10 August 2015, 19:51:13 UTC 
strbuf_read(): skip unnecessary strbuf_grow() at eof
 
The loop in strbuf_read() uses xread() repeatedly while extending
the strbuf until the call returns zero.  If the buffer is
sufficiently large to begin with, this results in xread()
returning the remainder of the file to the end (returning
non-zero), the loop extending the strbuf, and then making another
call to xread() to have it return zero.

By using read_in_full(), we can tell when the read reached the end
of file: when it returns less than was requested, it's eof.  This
way we can avoid an extra iteration that allocates an extra 8kB
that is never used.

Signed-off-by: Jim Hill <gjthill@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 282616c
Raw File
write_or_die.c 
#include "cache.h"

static void check_pipe(int err)
{
	if (err == EPIPE) {
		signal(SIGPIPE, SIG_DFL);
		raise(SIGPIPE);
		/* Should never happen, but just in case... */
		exit(141);
	}
}

/*
 * Some cases use stdio, but want to flush after the write
 * to get error handling (and to get better interactive
 * behaviour - not buffering excessively).
 *
 * Of course, if the flush happened within the write itself,
 * we've already lost the error code, and cannot report it any
 * more. So we just ignore that case instead (and hope we get
 * the right error code on the flush).
 *
 * If the file handle is stdout, and stdout is a file, then skip the
 * flush entirely since it's not needed.
 */
void maybe_flush_or_die(FILE *f, const char *desc)
{
	static int skip_stdout_flush = -1;
	struct stat st;
	char *cp;

	if (f == stdout) {
		if (skip_stdout_flush < 0) {
			cp = getenv("GIT_FLUSH");
			if (cp)
				skip_stdout_flush = (atoi(cp) == 0);
			else if ((fstat(fileno(stdout), &st) == 0) &&
				 S_ISREG(st.st_mode))
				skip_stdout_flush = 1;
			else
				skip_stdout_flush = 0;
		}
		if (skip_stdout_flush && !ferror(f))
			return;
	}
	if (fflush(f)) {
		check_pipe(errno);
		die_errno("write failure on '%s'", desc);
	}
}

void fsync_or_die(int fd, const char *msg)
{
	if (fsync(fd) < 0) {
		die_errno("fsync error on '%s'", msg);
	}
}

void write_or_die(int fd, const void *buf, size_t count)
{
	if (write_in_full(fd, buf, count) < 0) {
		check_pipe(errno);
		die_errno("write error");
	}
}

int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg)
{
	if (write_in_full(fd, buf, count) < 0) {
		check_pipe(errno);
		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)
{
	if (write_in_full(fd, buf, count) < 0) {
		fprintf(stderr, "%s: write error (%s)\n",
			msg, strerror(errno));
		return 0;
	}

	return 1;
}
back to top