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, 102 insertions, 0 deletions

diff --git a/inc/abrtlib.h b/inc/abrtlib.h
new file mode 100644
index 00000000..82ad3443
--- /dev/null
+++ b/inc/abrtlib.h
@@ -0,0 +1,102 @@
+/*
+ * Utility routines.
+ *
+ * Licensed under GPLv2, see file COPYING in this tarball for details.
+ */
+#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>
+
+/* Some libc's forget to declare these, do it ourself */
+extern char **environ;
+#if defined(__GLIBC__) && __GLIBC__ < 2
+int vdprintf(int d, const char *format, va_list ap);
+#endif
+
+
+#define NORETURN __attribute__ ((noreturn))
+
+
+/* Logging */
+enum {
+	LOGMODE_NONE = 0,
+	LOGMODE_STDIO = (1 << 0),
+	LOGMODE_SYSLOG = (1 << 1),
+	LOGMODE_BOTH = LOGMODE_SYSLOG + LOGMODE_STDIO,
+};
+extern const char *msg_prefix;
+extern const char *msg_eol;
+extern int logmode;
+extern int xfunc_error_retval;
+extern void xfunc_die(void) NORETURN;
+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 simple_perror_msg(const char *s);
+extern void perror_msg_and_die(const char *s, ...) __attribute__ ((noreturn, format (printf, 1, 2)));
+extern void simple_perror_msg_and_die(const char *s) NORETURN;
+extern void perror_nomsg_and_die(void) NORETURN;
+extern void perror_nomsg(void);
+extern void verror_msg(const char *s, va_list p, const char *strerr);
+/* This is a macro since it collides with log() from math.h */
+#undef log
+#define log(...) error_msg(__VA_ARGS__)
+
+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);
+
+extern ssize_t safe_read(int fd, void *buf, size_t count);
+// NB: will return short read on error, not -1,
+// if some data was read before error occurred
+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);
+// NB: will return short write on error, not -1,
+// if some data was written before error occurred
+extern ssize_t full_write(int fd, const void *buf, size_t count);
+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, ...);