Make read_in_full() and write_in_full() consistent with xread() and xwrite()

xread() and xwrite() return ssize_t values as their native POSIX
counterparts read(2) and write(2).

To be consistent, read_in_full() and write_in_full() should also return
ssize_t values.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -726,8 +726,8 @@ extern const char *git_log_output_encoding;
 extern void maybe_flush_or_die(FILE *, const char *);
 extern int copy_fd(int ifd, int ofd);
 extern int copy_file(const char *dst, const char *src, int mode);
-extern int read_in_full(int fd, void *buf, size_t count);
-extern int write_in_full(int fd, const void *buf, size_t count);
+extern ssize_t read_in_full(int fd, void *buf, size_t count);
+extern ssize_t write_in_full(int fd, const void *buf, size_t count);
 extern void write_or_die(int fd, const void *buf, size_t count);
 extern int write_or_whine(int fd, const void *buf, size_t count, const char *msg);
 extern int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg);

path.c

@@ -91,7 +91,8 @@ int validate_headref(const char *path)
 	struct stat st;
 	char *buf, buffer[256];
 	unsigned char sha1[20];
-	int len, fd;
+	int fd;
+	ssize_t len;
 
 	if (lstat(path, &st) < 0)
 		return -1;

refs.c

@@ -368,7 +368,8 @@ int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *re
 
 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 {
-	int depth = MAXDEPTH, len;
+	int depth = MAXDEPTH;
+	ssize_t len;
 	char buffer[256];
 	static char ref_buffer[256];
 

write_or_die.c

@@ -40,7 +40,7 @@ void maybe_flush_or_die(FILE *f, const char *desc)
 	}
 }
 
-int read_in_full(int fd, void *buf, size_t count)
+ssize_t read_in_full(int fd, void *buf, size_t count)
 {
 	char *p = buf;
 	ssize_t total = 0;
@@ -57,7 +57,7 @@ int read_in_full(int fd, void *buf, size_t count)
 	return total;
 }
 
-int write_in_full(int fd, const void *buf, size_t count)
+ssize_t write_in_full(int fd, const void *buf, size_t count)
 {
 	const char *p = buf;
 	ssize_t total = 0;