From f9eed9cc42dee01ac16a4dd968607f0ac84667c6 Mon Sep 17 00:00:00 2001
From: Jeremy Kerr <jeremy.kerr@canonical.com>
Date: Fri, 24 Aug 2012 19:58:21 +0800
Subject: [PATCH] fileio: Add fileio_read_file_noerror()

We may want to read files which can be absent. In this case, we don't
want to print an error.

This change adds fileio_read_file_noerror(), which suppresses error
output.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
---
 src/fileio.c | 41 +++++++++++++++++++++++++----------------
 src/fileio.h |  2 ++
 2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/src/fileio.c b/src/fileio.c
index f55d3a4..faab3b7 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -33,7 +33,7 @@
 #include <stdio.h>
 #include <fcntl.h>
 #include <unistd.h>
-#include <sys/stat.h>
+#include <string.h>
 #include <sys/stat.h>
 
 #include <openssl/bio.h>
@@ -45,6 +45,8 @@
 
 #include "fileio.h"
 
+#define FLAG_NOERROR	(1<<0)
+
 EVP_PKEY *fileio_read_pkey(const char *filename)
 {
 	EVP_PKEY *key = NULL;
@@ -86,8 +88,8 @@ out:
 	return cert;
 }
 
-int fileio_read_file(void *ctx, const char *filename,
-		 uint8_t **out_buf, size_t *out_len)
+static int __fileio_read_file(void *ctx, const char *filename,
+		 uint8_t **out_buf, size_t *out_len, int flags)
 {
 	struct stat statbuf;
 	uint8_t *buf;
@@ -97,29 +99,21 @@ int fileio_read_file(void *ctx, const char *filename,
 	rc = -1;
 
 	fd = open(filename, O_RDONLY);
-	if (fd < 0) {
-		perror("open");
+	if (fd < 0)
 		goto out;
-	}
 
 	rc = fstat(fd, &statbuf);
-	if (rc) {
-		perror("fstat");
+	if (rc)
 		goto out;
-	}
 
 	len = statbuf.st_size;
 
 	buf = talloc_array(ctx, uint8_t, len);
-	if (!buf) {
-		perror("talloc");
+	if (!buf)
 		goto out;
-	}
 
-	if (!read_all(fd, buf, len)) {
-		perror("read_all");
+	if (!read_all(fd, buf, len))
 		goto out;
-	}
 
 	rc = 0;
 
@@ -127,7 +121,9 @@ out:
 	if (fd >= 0)
 		close(fd);
 	if (rc) {
-		fprintf(stderr, "Error reading file %s\n", filename);
+		if (!(flags & FLAG_NOERROR))
+			fprintf(stderr, "Error reading file %s: %s\n",
+					filename, strerror(errno));
 	} else {
 		*out_buf = buf;
 		*out_len = len;
@@ -136,6 +132,19 @@ out:
 
 }
 
+int fileio_read_file(void *ctx, const char *filename,
+		 uint8_t **out_buf, size_t *out_len)
+{
+	return __fileio_read_file(ctx, filename, out_buf, out_len, 0);
+}
+
+int fileio_read_file_noerror(void *ctx, const char *filename,
+		 uint8_t **out_buf, size_t *out_len)
+{
+	return __fileio_read_file(ctx, filename, out_buf, out_len,
+			FLAG_NOERROR);
+}
+
 int fileio_write_file(const char *filename, uint8_t *buf, size_t len)
 {
 	int fd;
diff --git a/src/fileio.h b/src/fileio.h
index 1673a06..52c3c12 100644
--- a/src/fileio.h
+++ b/src/fileio.h
@@ -42,6 +42,8 @@ X509 *fileio_read_cert(const char *filename);
 
 int fileio_read_file(void *ctx, const char *filename,
 		uint8_t **out_buf, size_t *out_len);
+int fileio_read_file_noerror(void *ctx, const char *filename,
+		 uint8_t **out_buf, size_t *out_len);
 int fileio_write_file(const char *filename, uint8_t *buf, size_t len);
 
 #endif /* FILEIO_H */