[CRIU] Re: [PATCH 3/4] pr_perror(): print error at the end of line

[Cyrill Gorcunov]

On Mon, Jan 30, 2012 at 09:57:12PM +0400, Pavel Emelyanov wrote:
> On 01/30/2012 09:25 PM, Cyrill Gorcunov wrote:
> > On Mon, Jan 30, 2012 at 09:18:39PM +0400, Kir Kolyshkin wrote:
> >> This is a standard convention to print error message (i.e. strerror(errno))
> >> at the end of line, like this:
> >>
> >> 	Cannot remove file: Permission denied
> >>
> >> So pr_perror is fixed to follow this convention (using GNU extension
> >> %m helps a lot here). Unfortunately, due to this we have to make
> >> pr_perror() print a new line character, too, so we had to strip it
> >> from the all pr_perror() invocations.
> >>
> >> Signed-off-by: Kir Kolyshkin <kir at openvz.org>
> >> ---
> > 
> > Hi Kir, actually I don't like it, we have a number of pr_ helpers
> > (the idea in first place was to be similar to pr_ helpers used
> >  in kernel) so this pr_perror become a special one from the whole
> > pr_ helpers set in terms of "implicit new line at the end".
> > 
> > Kir, can we somehow bring back "explicit \n" at the end somehow?
> 
> I have the same question.
> 
> If it requires some non-trivial things to code, then I don't insist, let's
> live with it and
> 
> Acked-by: Pavel Emelyanov <xemul at parallels.com>
> 

Kir, might be something like below? 

	Cyrill
---
From: Cyrill Gorcunov <gorcunov at openvz.org>
Date: Mon, 30 Jan 2012 22:30:52 +0400
Subject: [PATCH] util: Modify pr_perror to follow perror convention

Ie to print system error message after all arguments
caller passed, for example

 | Error (crtools.c:249): Can't open '~/testing': No such file or directory

preserving new line if it was present in caller format.

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 include/util.h |    8 ++------
 util.c         |   25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/include/util.h b/include/util.h
index efe1b03..7198cde 100644
--- a/include/util.h
+++ b/include/util.h
@@ -17,6 +17,7 @@
 #include "types.h"
 
 extern void printk(const char *format, ...);
+extern void printk_strerrno(const char *format, ...);
 
 #define PREF_SHIFT_OP(pref, op, size)	((size) op (pref ##BYTES_SHIFT))
 #define KBYTES_SHIFT	10
@@ -35,6 +36,7 @@ extern void printk(const char *format, ...);
 #define pr_err(fmt, ...)	printk("Error (%s:%d): " fmt, __FILE__, __LINE__, ##__VA_ARGS__)
 #define pr_panic(fmt, ...)	printk("PANIC (%s:%d): " fmt, __FILE__, __LINE__, ##__VA_ARGS__)
 #define pr_warning(fmt, ...)	printk("Warning (%s:%d): " fmt, __FILE__, __LINE__, ##__VA_ARGS__)
+#define pr_perror(fmt, ...)	printk_strerrno("Error (%s:%d): " fmt, __FILE__, __LINE__, ##__VA_ARGS__)
 
 #define pr_err_jmp(label)					\
 	do {							\
@@ -81,12 +83,6 @@ extern void printk(const char *format, ...);
 		exit(1);					\
 	} while (0)
 
-#define pr_perror(fmt, ...)					\
-	do {							\
-		pr_err("%s: " fmt,  strerror(errno),		\
-			##__VA_ARGS__);				\
-	} while (0)
-
 #ifndef BUG_ON_HANDLER
 
 #ifdef CR_NOGLIBC
diff --git a/util.c b/util.c
index de22151..1bff4a7 100644
--- a/util.c
+++ b/util.c
@@ -47,6 +47,31 @@ void printk(const char *format, ...)
 	va_end(params);
 }
 
+void printk_strerrno(const char *format, ...)
+{
+	char buf[1024];
+	va_list params;
+	int npos;
+
+	va_start(params, format);
+	vsnprintf(buf, sizeof(buf), format, params);
+	va_end(params);
+
+	npos = strlen(buf) - 1;
+	if (buf[npos] == '\n')
+		buf[npos] = '\0';
+	else
+		npos = -1;
+
+	strncat(buf, ": ", sizeof(buf));
+	strncat(buf, strerror(errno), sizeof(buf));
+
+	if (npos != -1)
+		strncat(buf, "\n", sizeof(buf));
+
+	dprintf(get_logfd(), "%s", buf);
+}
+
 void hex_dump(void *addr, unsigned long len)
 {
 	unsigned char *p = addr;
-- 
1.7.7.6