Rewrite sprintf_alloc.

The example in printf(3) that this was taken from should not be used as
it ignores negative return codes from vsnprintf, instead allocating more
memory. Given an error from vsnprintf, this would loop until the process'
virtual memory is exhausted.

So we just exit in the event of a problem instead.

git-svn-id: http://opkg.googlecode.com/svn/trunk@581 e8e0d7a0-c8d9-11dd-a880-a1081c7ac358

2 files changed, 19 insertions, 35 deletions

diff --git a/libopkg/sprintf_alloc.c b/libopkg/sprintf_alloc.c
index 08c56bf..e2513ec 100644
--- a/libopkg/sprintf_alloc.c
+++ b/libopkg/sprintf_alloc.c
@@ -1,8 +1,6 @@
 /* sprintf_alloc.c -- like sprintf with memory allocation
 
-   Carl D. Worth
-
-   Copyright (C) 2001 University of Southern California
+   Copyright (C) 2010 Ubiq Technologies <graham.gower@gmail.com>
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -20,46 +18,32 @@
 #include "sprintf_alloc.h"
 #include "libbb/libbb.h"
 
-int sprintf_alloc(char **str, const char *fmt, ...)
+void
+sprintf_alloc(char **str, const char *fmt, ...)
 {
 	va_list ap;
 	int n;
-	unsigned size = 100;
-
-	if (!str) {
-		opkg_msg(ERROR, "Internal error: str=NULL.\n");
-		return -1;
-	}
-	if (!fmt) {
-		opkg_msg(ERROR, "Internal error: fmt=NULL.\n");
-		return -1;
-	}
-
-	/* On x86_64 systems, any strings over 100 were segfaulting.
-	   It seems that the ap needs to be reinitalized before every
-	   use of the v*printf() functions. I pulled the functionality out
-	   of vsprintf_alloc and combined it all here instead.
-	*/
-
-
-	/* ripped more or less straight out of PRINTF(3) */
+	unsigned int size = 1;
 
 	*str = xcalloc(1, size);
 
-	while (1) {
+	for (;;) {
 		va_start(ap, fmt);
 		n = vsnprintf (*str, size, fmt, ap);
 		va_end(ap);
-		/* If that worked, return the size. */
-		if (n > -1 && n < size)
-			return n;
-		/* Else try again with more space. */
-		if (n > -1)    /* glibc 2.1 */
-			size = n+1; /* precisely what is needed */
-		else           /* glibc 2.0 */
-			size *= 2;  /* twice the old size */
+
+		if (n < 0) {
+			fprintf(stderr, "%s: encountered an output or encoding"
+					" error during vsnprintf.\n",
+					__FUNCTION__);
+			exit(EXIT_FAILURE);
+		}
+
+		if (n < size)
+			break;
+
+		/* Truncated, try again with more space. */
+		size = n+1;
 		*str = xrealloc(*str, size);
 	}
-
-	return -1; /* Just to be correct - it probably won't get here */
 }
diff --git a/libopkg/sprintf_alloc.h b/libopkg/sprintf_alloc.h
index 3d68d69..bcf42a4 100644
--- a/libopkg/sprintf_alloc.h
+++ b/libopkg/sprintf_alloc.h
@@ -18,6 +18,6 @@
 #ifndef SPRINTF_ALLOC_H
 #define SPRINTF_ALLOC_H
 
-int sprintf_alloc(char **str, const char *fmt, ...);
+void sprintf_alloc(char **str, const char *fmt, ...);
 
 #endif