add utility functions

Logging machinery provided by this patch consists of several functions:

+extern void error_msg(const char *s, ...) __attribute__ ((format (printf, 1, 2)));
+extern void error_msg_and_die(const char *s, ...) __attribute__ ((noreturn, format (printf, 1, 2)));
+extern void perror_msg(const char *s, ...) __attribute__ ((format (printf, 1, 2)));
+extern void perror_msg_and_die(const char *s, ...) __attribute__ ((noreturn, format (printf, 1, 2)));
+/* This is a macro since it collides with log() from math.h */
+#undef log
+#define log(...) error_msg(__VA_ARGS__)

They are taking printf-style format strings. perror_msg_xxx functions append
an errno string after the message: "xxx xxx xxx: No such file or directory"
if errno is != 0. xxx_and_die functions do not return.

All functions also ensure that the message ends with "\n",
meaning that you do not need to add it into the message,
but if you do, an extra "\n" will not be added.

All functions ensure that the string is written in a single write() call,
thus if two processes output to the same terminal or file, messages
don't get intermingled.

Ordinarily, messages go to the stderr. By setting global variable "logmode"
to LOGMODE_SYSLOG or LOGMODE_NONE, they can be sent to syslog or be suppressed.
Standard setting is LOGMODE_STDIO. LOGMODE_STDIO + LOGMODE_SYSLOG works too.
Usually it is set by main() as needed, and then you can fearlessly use
[p]error_msg[_and_die]() and be sure that message goes to the right place.

+enum {
+       LOGMODE_NONE = 0,
+       LOGMODE_STDIO = (1 << 0),
+       LOGMODE_SYSLOG = (1 << 1),
+       LOGMODE_BOTH = LOGMODE_SYSLOG + LOGMODE_STDIO,
+};
+extern int logmode;

Exit code of xxx_and_die variants is controlled by the global variable

+extern int xfunc_error_retval;

By default it is = 1.

Logging infrastructure uses a few other functions, which I find
useful on their own, and since I discussed them with Zdenek
and he thinks that they may be useful too, they are included
in the patch also.

The first group is "malloc or die" group:

+void* malloc_or_warn(size_t size);
+void* xmalloc(size_t size);
+void* xrealloc(void *ptr, size_t size);
+void* xzalloc(size_t size);
+char* xstrdup(const char *s);
+char* xstrndup(const char *s, int n);

They are basically versions of malloc etc which exit
on failure.

The next group are simple I/O wrappers:

+extern ssize_t safe_read(int fd, void *buf, size_t count);
+extern ssize_t full_read(int fd, void *buf, size_t count);
+extern void xread(int fd, void *buf, size_t count);
+extern ssize_t safe_write(int fd, const void *buf, size_t count);
+extern ssize_t full_write(int fd, const void *buf, size_t count);

safe_xxx deal with the fact that read and write operations
may "fail" with EINTR and in many cases we want to just
repeat the operation. full_xxx deal with the fact that
read and write are not guaranteed to read or write exact amount,
they may to transfer less bytes. In this case we need to loop.

The next group are the "x functions":

+extern void xwrite(int fd, const void *buf, size_t count);
+extern void xwrite_str(int fd, const char *str);
+void xpipe(int filedes[2]);
+void xdup2(int from, int to);
+off_t xlseek(int fd, off_t offset, int whence);
+void xsetenv(const char *key, const char *value);
+int xsocket(int domain, int type, int protocol);
+void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen);
+void xlisten(int s, int backlog);
+ssize_t xsendto(int s, const void *buf, size_t len, const struct sockaddr *to, socklen_t tolen);
+void xstat(const char *name, struct stat *stat_buf);
+void xmove_fd(int from, int to);
+char* xasprintf(const char *format, ...);

They are similar to xmalloc in a sense that they exit on the failure.
Most of them closely resemble corresponding libc functions.

xmove_fd() is a wrapper for typical idiom "if (fd1!=fd2) dup2(fd1,fd2)",
with error checking on dup2 failure added.

xasprintf() is a "strcat on steroids". It's a printf-like function
which returns a malloced string. In my experience, it is surprisingly
useful: it makes complex concatenations easy in C.

All these functions are declared in a new header, inc/abrtlib.h.
It also contains a list of #includes:

+#include <ctype.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <string.h>
+#include <sys/poll.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <termios.h>
+#include <time.h>
+#include <unistd.h>
+/* Try to pull in PATH_MAX */
+#include <limits.h>
+#include <sys/param.h>
+#ifndef PATH_MAX
+# define PATH_MAX 256
+#endif
+#include <pwd.h>
+#include <grp.h>

The rationale to do so is that these headers are pretty standard,
and by having them included in this one file, we won't need to
add #includes into many .c[pp] files later. The slowdown
from gcc parsing these headers even if they are not needed
is not worth spending time on optimizing out.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 214 insertions, 0 deletions

diff --git a/lib/Utils/xfuncs.cpp b/lib/Utils/xfuncs.cpp
new file mode 100644
index 0000000..ad67ec6
--- /dev/null
+++ b/lib/Utils/xfuncs.cpp
@@ -0,0 +1,214 @@
+/*
+ * Utility routines.
+ *
+ * Licensed under GPLv2, see file COPYING in this tarball for details.
+ */
+#include "abrtlib.h"
+
+static const char msg_memory_exhausted[] = "memory exhausted";
+
+void* malloc_or_warn(size_t size)
+{
+	void *ptr = malloc(size);
+	if (ptr == NULL && size != 0)
+		error_msg(msg_memory_exhausted);
+	return ptr;
+}
+
+// Die if we can't allocate size bytes of memory.
+void* xmalloc(size_t size)
+{
+	void *ptr = malloc(size);
+	if (ptr == NULL && size != 0)
+		error_msg_and_die(msg_memory_exhausted);
+	return ptr;
+}
+
+// Die if we can't resize previously allocated memory.  (This returns a pointer
+// to the new memory, which may or may not be the same as the old memory.
+// It'll copy the contents to a new chunk and free the old one if necessary.)
+void* xrealloc(void *ptr, size_t size)
+{
+	ptr = realloc(ptr, size);
+	if (ptr == NULL && size != 0)
+		error_msg_and_die(msg_memory_exhausted);
+	return ptr;
+}
+
+// Die if we can't allocate and zero size bytes of memory.
+void* xzalloc(size_t size)
+{
+	void *ptr = xmalloc(size);
+	memset(ptr, 0, size);
+	return ptr;
+}
+
+// Die if we can't copy a string to freshly allocated memory.
+char* xstrdup(const char *s)
+{
+	char *t;
+
+	if (s == NULL)
+		return NULL;
+
+	t = strdup(s);
+
+	if (t == NULL)
+		error_msg_and_die(msg_memory_exhausted);
+
+	return t;
+}
+
+// Die if we can't allocate n+1 bytes (space for the null terminator) and copy
+// the (possibly truncated to length n) string into it.
+char* xstrndup(const char *s, int n)
+{
+	int m;
+	char *t;
+
+	/* We can just xmalloc(n+1) and strncpy into it, */
+	/* but think about xstrndup("abc", 10000) wastage! */
+	m = n;
+	t = (char*) s;
+	while (m) {
+		if (!*t) break;
+		m--;
+		t++;
+	}
+	n -= m;
+	t = (char*) xmalloc(n + 1);
+	t[n] = '\0';
+
+	return (char*) memcpy(t, s, n);
+}
+
+void xpipe(int filedes[2])
+{
+	if (pipe(filedes))
+		perror_msg_and_die("can't create pipe");
+}
+
+void xdup2(int from, int to)
+{
+	if (dup2(from, to) != to)
+		perror_msg_and_die("can't duplicate file descriptor");
+}
+
+// "Renumber" opened fd
+void xmove_fd(int from, int to)
+{
+	if (from == to)
+		return;
+	xdup2(from, to);
+	close(from);
+}
+
+// Die with an error message if we can't write the entire buffer.
+void xwrite(int fd, const void *buf, size_t count)
+{
+	if (count) {
+		ssize_t size = full_write(fd, buf, count);
+		if ((size_t)size != count)
+			error_msg_and_die("short write");
+	}
+}
+void xwrite_str(int fd, const char *str)
+{
+	xwrite(fd, str, strlen(str));
+}
+
+// Die with an error message if we can't lseek to the right spot.
+off_t xlseek(int fd, off_t offset, int whence)
+{
+	off_t off = lseek(fd, offset, whence);
+	if (off == (off_t)-1) {
+		if (whence == SEEK_SET)
+			perror_msg_and_die("lseek(%llu)", (long long)offset);
+		perror_msg_and_die("lseek");
+	}
+	return off;
+}
+
+// Die with an error message if we can't malloc() enough space and do an
+// sprintf() into that space.
+char* xasprintf(const char *format, ...)
+{
+	va_list p;
+	int r;
+	char *string_ptr;
+
+#if 1
+	// GNU extension
+	va_start(p, format);
+	r = vasprintf(&string_ptr, format, p);
+	va_end(p);
+#else
+	// Bloat for systems that haven't got the GNU extension.
+	va_start(p, format);
+	r = vsnprintf(NULL, 0, format, p);
+	va_end(p);
+	string_ptr = xmalloc(r+1);
+	va_start(p, format);
+	r = vsnprintf(string_ptr, r+1, format, p);
+	va_end(p);
+#endif
+
+	if (r < 0)
+		error_msg_and_die(msg_memory_exhausted);
+	return string_ptr;
+}
+
+void xsetenv(const char *key, const char *value)
+{
+	if (setenv(key, value, 1))
+		error_msg_and_die(msg_memory_exhausted);
+}
+
+// Die with an error message if we can't open a new socket.
+int xsocket(int domain, int type, int protocol)
+{
+	int r = socket(domain, type, protocol);
+
+	if (r < 0) {
+		/* Hijack vaguely related config option */
+		const char *s = "INET";
+		if (domain == AF_PACKET) s = "PACKET";
+		if (domain == AF_NETLINK) s = "NETLINK";
+		if (domain == AF_INET6) s = "INET6";
+		perror_msg_and_die("socket(AF_%s)", s);
+	}
+
+	return r;
+}
+
+// Die with an error message if we can't bind a socket to an address.
+void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen)
+{
+	if (bind(sockfd, my_addr, addrlen)) perror_msg_and_die("bind");
+}
+
+// Die with an error message if we can't listen for connections on a socket.
+void xlisten(int s, int backlog)
+{
+	if (listen(s, backlog)) perror_msg_and_die("listen");
+}
+
+// Die with an error message if sendto failed.
+// Return bytes sent otherwise
+ssize_t xsendto(int s, const void *buf, size_t len, const struct sockaddr *to,
+				socklen_t tolen)
+{
+	ssize_t ret = sendto(s, buf, len, 0, to, tolen);
+	if (ret < 0) {
+		close(s);
+		perror_msg_and_die("sendto");
+	}
+	return ret;
+}
+
+// xstat() - a stat() which dies on failure with meaningful error message
+void xstat(const char *name, struct stat *stat_buf)
+{
+	if (stat(name, stat_buf))
+		perror_msg_and_die("can't stat '%s'", name);
+}