* Hook output functions (like printf(3)) with LD_PRELOAD to color stderr (or
* other file descriptors).
*
- * Copyright (C) 2013 Simon Ruderich
+ * Copyright (C) 2013-2018 Simon Ruderich
*
* 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
#include <config.h>
+#include "compiler.h"
+
/* Must be loaded before the following headers. */
#include "ldpreload.h"
+/* Disable assert()s if not compiled with --enable-debug. */
+#ifndef DEBUG
+# define NDEBUG
+#endif
+
+#ifndef TLS
+# define TLS
+#endif
+
+#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
+#include <sys/stat.h>
#include <unistd.h>
+#ifdef HAVE_ERR_H
+# include <err.h>
+#endif
#ifdef HAVE_ERROR_H
# include <error.h>
#endif
+#ifdef HAVE_STRUCT__IO_FILE__FILENO
+# include <libio.h>
+#endif
-/* Conflicting declaration in glibc. */
-#undef fwrite_unlocked
+/* The following functions may be macros. Undefine them or they cause build
+ * failures when used in our hook macros below. */
+
+/* In glibc, real fwrite_unlocked() is called in macro. */
+#ifdef HAVE_FWRITE_UNLOCKED
+# undef fwrite_unlocked
+#endif
+/* In Clang when compiling with hardening flags (fortify) on Debian Wheezy. */
+#undef printf
+#undef fprintf
+/* On FreeBSD (9.1), __swbuf() is used instead of these macros. */
+#ifdef HAVE___SWBUF
+# undef putc
+# undef putc_unlocked
+# undef putchar
+# undef putchar_unlocked
+#endif
/* Used by various functions, including debug(). */
static int initialized;
/* Force hooked writes even when not writing to a tty. Used for tests. */
static int force_write_to_non_tty;
+/* Was ENV_NAME_FDS found and used when init_from_environment() was called?
+ * This is not true if the process set it manually after initialization. */
+static int used_fds_set_by_user;
+/* Was any of our handle_*_pre()/handle_*_post() functions called recursively?
+ * If so don't print the pre/post string for the recursive calls. This is
+ * necessary on some systems (e.g. FreeBSD 9.1) which call multiple hooked
+ * functions while printing a string (e.g. a FILE * and a fd hook function is
+ * called). This is not thread-safe if TLS is not available. */
+static TLS int handle_recursive;
#include "constants.h"
-#ifdef DEBUG
+#ifdef WARNING
# include "debug.h"
#endif
-/* Should the "action" handler be invoked for this file descriptor? */
-static int check_handle_fd(int fd) {
- /* Load state from environment. Only necessary once per process. */
- if (!initialized) {
- init_from_environment();
- }
+/* See hookmacros.h for the decision if a function call is colored. */
- /* tracked_fds_find() is most likely faster than calling isatty(),
- * therefore check if we are tracking this file descriptor first. */
- if (!tracked_fds_find(fd)) {
- return 0;
- }
- /* Never touch anything not going to a terminal - unless we are explicitly
- * asked to do so. */
- if (!force_write_to_non_tty && !isatty(fd)) {
- return 0;
- }
+/* Prevent inlining into hook functions because it may increase the number of
+ * spilled registers unnecessarily. As it's not called very often accept the
+ * additional call. */
+static int isatty_noinline(int fd) noinline;
+static int isatty_noinline(int fd) {
+ assert(fd >= 0);
+
+ int saved_errno = errno;
+ int result = isatty(fd);
+ errno = saved_errno;
- return 1;
+ return result;
}
+
static void dup_fd(int oldfd, int newfd) {
#ifdef DEBUG
debug("%3d -> %3d\t\t\t[%d]\n", oldfd, newfd, getpid());
#endif
- if (!initialized) {
+ assert(oldfd >= 0 && newfd >= 0);
+
+ if (unlikely(!initialized)) {
init_from_environment();
}
debug("%3d -> .\t\t\t[%d]\n", fd, getpid());
#endif
- if (!initialized) {
+ assert(fd >= 0);
+
+ if (unlikely(!initialized)) {
init_from_environment();
}
/* "Action" handlers called when a file descriptor is matched. */
-static char *pre_string;
+static char const *pre_string;
static size_t pre_string_size;
-static char *post_string;
+static char const *post_string;
static size_t post_string_size;
/* Load alternative pre/post strings from the environment if available, fall
* back to default values. */
-inline static void init_pre_post_string() {
+static void init_pre_post_string(void) {
pre_string = getenv(ENV_NAME_PRE_STRING);
if (!pre_string) {
pre_string = DEFAULT_PRE_STRING;
post_string_size = strlen(post_string);
}
-static void handle_fd_pre(int fd, int action) {
- (void)action;
+/* Don't inline any of the pre/post functions. Keep the hook function as small
+ * as possible for speed reasons. */
+static void handle_fd_pre(int fd) noinline;
+static void handle_fd_post(int fd) noinline;
+static void handle_file_pre(FILE *stream) noinline;
+static void handle_file_post(FILE *stream) noinline;
+
+static void handle_fd_pre(int fd) {
+ if (handle_recursive++ > 0) {
+ return;
+ }
+
+ int saved_errno = errno;
- if (!pre_string || !post_string) {
+ if (unlikely(!pre_string)) {
init_pre_post_string();
}
DLSYM_FUNCTION(real_write, "write");
real_write(fd, pre_string, pre_string_size);
+
+ errno = saved_errno;
}
-static void handle_fd_post(int fd, int action) {
- (void)action;
+static void handle_fd_post(int fd) {
+ if (--handle_recursive > 0) {
+ return;
+ }
+
+ int saved_errno = errno;
/* write() already loaded above in handle_fd_pre(). */
real_write(fd, post_string, post_string_size);
+
+ errno = saved_errno;
}
-static void handle_file_pre(FILE *stream, int action) {
- (void)action;
+static void handle_file_pre(FILE *stream) {
+ if (handle_recursive++ > 0) {
+ return;
+ }
+
+ int saved_errno = errno;
- if (!pre_string || !post_string) {
+ if (unlikely(!pre_string)) {
init_pre_post_string();
}
DLSYM_FUNCTION(real_fwrite, "fwrite");
real_fwrite(pre_string, pre_string_size, 1, stream);
+
+ errno = saved_errno;
}
-static void handle_file_post(FILE *stream, int action) {
- (void)action;
+static void handle_file_post(FILE *stream) {
+ if (--handle_recursive > 0) {
+ return;
+ }
+
+ int saved_errno = errno;
/* fwrite() already loaded above in handle_file_pre(). */
real_fwrite(post_string, post_string_size, 1, stream);
+
+ errno = saved_errno;
}
int, c, FILE *, stream)
HOOK_FILE2(int, putc, stream,
int, c, FILE *, stream)
+/* The glibc uses a macro for putc() which expands to _IO_putc(). However
+ * sometimes the raw putc() is used as well, not sure why. Make sure to hook
+ * it too. */
+#ifdef putc
+# undef putc
+HOOK_FILE2(int, putc, stream,
+ int, c, FILE *, stream)
+#endif
HOOK_FILE1(int, putchar, stdout,
int, c)
HOOK_FILE1(int, puts, stdout,
FILE *, stream, int, flag, char const *, format, va_list, ap)
/* unlocked_stdio(3), only functions from above are hooked */
+#ifdef HAVE_FWRITE_UNLOCKED
HOOK_FILE4(size_t, fwrite_unlocked, stream,
void const *, ptr, size_t, size, size_t, nmemb, FILE *, stream)
+#endif
+#ifdef HAVE_FPUTS_UNLOCKED
HOOK_FILE2(int, fputs_unlocked, stream,
char const *, s, FILE *, stream)
+#endif
+#ifdef HAVE_FPUTC_UNLOCKED
HOOK_FILE2(int, fputc_unlocked, stream,
int, c, FILE *, stream)
+#endif
HOOK_FILE2(int, putc_unlocked, stream,
int, c, FILE *, stream)
HOOK_FILE1(int, putchar_unlocked, stdout,
int, c)
-HOOK_FILE1(int, puts_unlocked, stdout,
- char const *, s)
+/* glibc defines (_IO_)putc_unlocked() to a macro which either updates the
+ * output buffer or calls __overflow(). As this code is inlined we can't
+ * handle the first case, but if __overflow() is called we can color that
+ * part. As writes to stderr are never buffered, __overflow() is always called
+ * and everything works fine. This is only a problem if stdout is dupped to
+ * stderr (which shouldn't be the case too often). */
+#if defined(HAVE_STRUCT__IO_FILE__FILENO) && defined(HAVE___OVERFLOW)
+/* _IO_FILE is glibc's representation of FILE. */
+HOOK_FILE2(int, __overflow, f, _IO_FILE *, f, int, ch)
+#endif
+/* Same for FreeBSD's libc. However it's more aggressive: The inline writing
+ * and __swbuf() are also used for normal output (e.g. putc()). Writing to
+ * stderr is still fine; it always calls __swbuf() as stderr is always
+ * unbuffered. */
+#ifdef HAVE___SWBUF
+HOOK_FILE2(int, __swbuf, f, int, c, FILE *, f)
+#endif
/* perror(3) */
HOOK_VOID1(void, perror, STDERR_FILENO,
char const *, s)
-/* error(3) */
+/* err(3), non standard BSD extension */
+#ifdef HAVE_ERR_H
+HOOK_VAR_VOID2(void, err, STDERR_FILENO, verr,
+ int, eval, char const *, fmt)
+HOOK_VAR_VOID2(void, errx, STDERR_FILENO, verrx,
+ int, eval, char const *, fmt)
+HOOK_VAR_VOID1(void, warn, STDERR_FILENO, vwarn,
+ char const *, fmt)
+HOOK_VAR_VOID1(void, warnx, STDERR_FILENO, vwarnx,
+ char const *, fmt)
+HOOK_FUNC_SIMPLE3(void, verr, int, eval, const char *, fmt, va_list, args) {
+ /* Can't use verr() directly as it terminates the process which prevents
+ * the post string from being printed. */
+ vwarn(fmt, args);
+ exit(eval);
+}
+HOOK_FUNC_SIMPLE3(void, verrx, int, eval, const char *, fmt, va_list, args) {
+ /* See verr(). */
+ vwarnx(fmt, args);
+ exit(eval);
+}
+HOOK_VOID2(void, vwarn, STDERR_FILENO,
+ char const *, fmt, va_list, args)
+HOOK_VOID2(void, vwarnx, STDERR_FILENO,
+ char const *, fmt, va_list, args)
+#endif
+
+/* error(3), non-standard GNU extension */
#ifdef HAVE_ERROR_H
-static void error_vararg(int status, int errnum,
- char const *filename, unsigned int linenum,
- char const *format, va_list ap) {
+static void error_vararg(int status, int errnum,
+ char const *filename, unsigned int linenum,
+ char const *format, va_list ap) {
static char const *last_filename;
static unsigned int last_linenum;
if (error_one_per_line
&& filename != NULL && linenum != 0
&& filename == last_filename && linenum == last_linenum) {
- return;
+ goto out;
}
last_filename = filename;
last_linenum = linenum;
fprintf(stderr, "\n");
+out:
if (status != 0) {
exit(status);
}
/* Hook functions which duplicate file descriptors to track them. */
-static int (*real_dup)(int);
-static int (*real_dup2)(int, int);
-static int (*real_dup3)(int, int, int);
-int dup(int oldfd) {
+/* int dup(int) */
+HOOK_FUNC_DEF1(int, dup, int, oldfd) {
int newfd;
DLSYM_FUNCTION(real_dup, "dup");
newfd = real_dup(oldfd);
- if (newfd != -1) {
- int saved_errno = errno;
+ if (newfd > -1) {
dup_fd(oldfd, newfd);
- errno = saved_errno;
}
return newfd;
}
-int dup2(int oldfd, int newfd) {
+/* int dup2(int, int) */
+HOOK_FUNC_DEF2(int, dup2, int, oldfd, int, newfd) {
DLSYM_FUNCTION(real_dup2, "dup2");
newfd = real_dup2(oldfd, newfd);
- if (newfd != -1) {
- int saved_errno = errno;
+ if (newfd > -1) {
dup_fd(oldfd, newfd);
- errno = saved_errno;
}
return newfd;
}
-int dup3(int oldfd, int newfd, int flags) {
+/* int dup3(int, int, int) */
+HOOK_FUNC_DEF3(int, dup3, int, oldfd, int, newfd, int, flags) {
DLSYM_FUNCTION(real_dup3, "dup3");
newfd = real_dup3(oldfd, newfd, flags);
- if (newfd != -1) {
- int saved_errno = errno;
+ if (newfd > -1) {
dup_fd(oldfd, newfd);
- errno = saved_errno;
}
return newfd;
}
-static int (*real_fcntl)(int, int, ...);
-int fcntl(int fd, int cmd, ...) {
+/* int fcntl(int, int, ...) */
+HOOK_FUNC_VAR_DEF2(int, fcntl, int, fd, int, cmd /*, ... */) {
int result;
va_list ap;
va_end(ap);
/* We only care about duping fds. */
- if (cmd == F_DUPFD && result != -1) {
- int saved_errno = errno;
+ if (cmd == F_DUPFD && result > -1) {
dup_fd(fd, result);
- errno = saved_errno;
}
return result;
}
-static int (*real_close)(int);
-int close(int fd) {
+/* int close(int) */
+HOOK_FUNC_DEF1(int, close, int, fd) {
DLSYM_FUNCTION(real_close, "close");
- close_fd(fd);
+ if (fd >= 0) {
+ close_fd(fd);
+ }
return real_close(fd);
}
-static int (*real_fclose)(FILE *);
-int fclose(FILE *fp) {
+/* int fclose(FILE *) */
+HOOK_FUNC_DEF1(int, fclose, FILE *, fp) {
+ int fd;
+
DLSYM_FUNCTION(real_fclose, "fclose");
- close_fd(fileno(fp));
+ if (fp != NULL && (fd = fileno(fp)) >= 0) {
+ close_fd(fd);
+ }
return real_fclose(fp);
}
* isn't allowed to perform any memory-modifications before the exec()
* (except the pid_t result variable of vfork()).
*
- * As some programs don't adhere to the standard (e.g. the "child" closes
- * or dups a descriptor before the exec()) and this breaks our tracking of
- * file descriptors (e.g. it gets closed in the parent as well), we just
- * fork() instead. This is in compliance with the POSIX standard and as
- * most systems use copy-on-write anyway not a performance issue. */
+ * As we have to store changes to the file descriptors in memory (e.g. the
+ * "child" closes or dups a descriptor before the exec()) and this
+ * modifies the parent as well due to the semantics of vfork() - thus
+ * breaking the requirements of vfork(), we just use fork instead(). This
+ * is in compliance with the POSIX standard and as most systems use
+ * copy-on-write anyway not a performance issue. */
return fork();
}
#endif
/* Hook execve() and the other exec*() functions. Some shells use exec*() with
* a custom environment which doesn't necessarily contain our updates to
- * ENV_NAME_FDS. It's also faster to update the environment only when
- * necessary, right before the exec() to pass it to the new process. */
+ * ENV_NAME_PRIVATE_FDS. It's also faster to update the environment only when
+ * necessary, right before the exec(), to pass it to the new program. */
-static int (*real_execve)(char const *filename, char * const argv[], char * const env[]);
-int execve(char const *filename, char * const argv[], char * const env[]) {
+/* int execve(char const *, char * const [], char * const []) */
+HOOK_FUNC_DEF3(int, execve, char const *, filename, char * const *, argv, char * const *, env) {
DLSYM_FUNCTION(real_execve, "execve");
- int found = 0;
- size_t index = 0;
+ char * const fake_env[] = {NULL};
+ if (env == NULL) {
+ env = fake_env;
+ }
- /* Count arguments and search for existing ENV_NAME_FDS environment
- * variable. */
+ /* Count environment variables. */
size_t count = 0;
char * const *x = env;
- while (*x) {
- if (!strncmp(*x, ENV_NAME_FDS "=", strlen(ENV_NAME_FDS) + 1)) {
- found = 1;
- index = count;
- }
-
- x++;
+ while (*x++) {
count++;
}
/* Terminating NULL. */
count++;
char *env_copy[count + 1 /* space for our new entry if necessary */];
- memcpy(env_copy, env, count * sizeof(char *));
/* Make sure the information from the environment is loaded. We can't just
* do nothing (like update_environment()) because the caller might pass a
init_from_environment();
}
- char fds_env[strlen(ENV_NAME_FDS) + 1 + update_environment_buffer_size()];
- strcpy(fds_env, ENV_NAME_FDS "=");
- update_environment_buffer(fds_env + strlen(ENV_NAME_FDS) + 1);
+ char fds_env[strlen(ENV_NAME_PRIVATE_FDS)
+ + 1 + update_environment_buffer_size()];
+ strcpy(fds_env, ENV_NAME_PRIVATE_FDS "=");
+ update_environment_buffer(fds_env + strlen(ENV_NAME_PRIVATE_FDS) + 1);
- if (found) {
- env_copy[index] = fds_env;
- } else {
- /* If the process removed ENV_NAME_FDS from the environment, re-add
- * it. */
- env_copy[count-1] = fds_env;
- env_copy[count] = NULL;
+ int found = 0;
+ char **x_copy = env_copy;
+
+ /* Copy the environment manually; allows skipping elements. */
+ x = env;
+ while ((*x_copy = *x)) {
+ /* Remove ENV_NAME_FDS if we've already used its value. The new
+ * program must use the updated list from ENV_NAME_PRIVATE_FDS. */
+ if (used_fds_set_by_user
+ && !strncmp(*x, ENV_NAME_FDS "=", strlen(ENV_NAME_FDS) + 1)) {
+ x++;
+ continue;
+ /* Update ENV_NAME_PRIVATE_FDS. */
+ } else if (!strncmp(*x, ENV_NAME_PRIVATE_FDS "=",
+ strlen(ENV_NAME_PRIVATE_FDS) + 1)) {
+ *x_copy = fds_env;
+ found = 1;
+ }
+
+ x++;
+ x_copy++;
+ }
+ /* The loop "condition" NULL-terminates env_copy. */
+
+ if (!found) {
+ /* If the process removed ENV_NAME_PRIVATE_FDS from the environment,
+ * re-add it. */
+ *x_copy++ = fds_env;
+ *x_copy++ = NULL;
}
return real_execve(filename, argv, env_copy);
/* Count arguments. */ \
size_t count = 1; /* arg */ \
va_start(ap, arg); \
- while (va_arg(ap, const char *)) { \
+ while (va_arg(ap, char *)) { \
count++; \
} \
va_end(ap); \
\
/* Copy varargs. */ \
char *args[count + 1 /* terminating NULL */]; \
- args[0] = (char *)arg; \
+ args[0] = (char *)arg; /* there's no other way around the cast */ \
\
size_t i = 1; \
va_start(ap, arg); \
int execl(char const *path, char const *arg, ...) {
EXECL_COPY_VARARGS(args);
- update_environment();
+ /* execv() updates the environment. */
return execv(path, args);
}
-
int execlp(char const *file, char const *arg, ...) {
EXECL_COPY_VARARGS(args);
- update_environment();
+ /* execvp() updates the environment. */
return execvp(file, args);
}
-
int execle(char const *path, char const *arg, ... /*, char * const envp[] */) {
+ char * const *envp;
+
EXECL_COPY_VARARGS_START(args);
/* Get envp[] located after arguments. */
- char * const *envp = va_arg(ap, char * const *);
+ envp = va_arg(ap, char * const *);
EXECL_COPY_VARARGS_END(args);
+ /* execve() updates the environment. */
return execve(path, args, envp);
}
-static int (*real_execv)(char const *path, char * const argv[]);
-int execv(char const *path, char * const argv[]) {
+/* int execv(char const *, char * const []) */
+HOOK_FUNC_DEF2(int, execv, char const *, path, char * const *, argv) {
DLSYM_FUNCTION(real_execv, "execv");
update_environment();
return real_execv(path, argv);
}
-static int (*real_execvp)(char const *path, char * const argv[]);
-int execvp(char const *path, char * const argv[]) {
+/* int execvp(char const *, char * const []) */
+HOOK_FUNC_DEF2(int, execvp, char const *, file, char * const *, argv) {
DLSYM_FUNCTION(real_execvp, "execvp");
update_environment();
- return real_execvp(path, argv);
+ return real_execvp(file, argv);
+}
+
+#ifdef HAVE_EXECVPE
+extern char **environ;
+int execvpe(char const *file, char * const argv[], char * const envp[]) {
+ int result;
+ char **old_environ = environ;
+
+ /* Fake the environment so we can reuse execvp(). */
+ environ = (char **)envp;
+
+ /* execvp() updates the environment. */
+ result = execvp(file, argv);
+
+ environ = old_environ;
+ return result;
}
+#endif
ruderich.org/simon / coloredstderr / coloredstderr.git / blobdiff