/* Must be loaded before the following headers. */
#include "ldpreload.h"
-/* FIXME: use correct declaration for fcntl() */
-#define fcntl fcntl_ignore
-
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
-#undef fcntl
/* Conflicting declaration in glibc. */
#undef fwrite_unlocked
static int (*real_close)(int);
static size_t (*real_fwrite)(const void *, size_t, size_t, FILE *);
+/* Did we already (try to) parse the environment and setup the necessary
+ * variables? */
+static int initialized;
+/* Force hooked writes even when not writing to a tty. Used for tests. */
+static int force_write_to_non_tty;
+
#include "constants.h"
#ifdef DEBUG
# include "debug.h"
#endif
-#include "macros.h"
+#include "hookmacros.h"
#include "trackfds.h"
/* Should the "action" handler be invoked for this file descriptor? */
static int check_handle_fd(int fd) {
- /* Never touch anything not going to a terminal. */
- if (!isatty(fd)) {
- return 0;
- }
-
/* Load state from environment. Only necessary once per process. */
- if (!tracked_fds) {
+ if (!initialized) {
init_from_environment();
}
+ /* 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;
+ }
+
if (tracked_fds_count == 0) {
return 0;
}
static void dup_fd(int oldfd, int newfd) {
#ifdef DEBUG
- debug("%d -> %d\t\t\t[%d]\n", oldfd, newfd, getpid());
+ debug("%3d -> %3d\t\t\t[%d]\n", oldfd, newfd, getpid());
#endif
- if (!tracked_fds) {
+ if (!initialized) {
init_from_environment();
}
if (tracked_fds_count == 0) {
if (tracked_fds_find(oldfd)) {
if (!tracked_fds_find(newfd)) {
tracked_fds_add(newfd);
- update_environment();
}
/* We are not tracking this file descriptor, remove newfd from the list
* (if present). */
} else {
- if (tracked_fds_remove(newfd)) {
- update_environment();
- }
+ tracked_fds_remove(newfd);
}
}
static void close_fd(int fd) {
#ifdef DEBUG
- debug("%d -> .\t\t\t[%d]\n", fd, getpid());
+ debug("%3d -> .\t\t\t[%d]\n", fd, getpid());
#endif
- if (!tracked_fds) {
+ if (!initialized) {
init_from_environment();
}
const char *, format, va_list, ap)
HOOK_FILE3(int, vfprintf, stream,
FILE *, stream, const char *, format, va_list, ap)
-/* Hardening functions (-D_FORTIFY_SOURCE=2). */
+/* Hardening functions (-D_FORTIFY_SOURCE=2), only functions from above */
HOOK_VAR_FILE2(int, __printf_chk, stdout, __vprintf_chk,
int, flag, const char *, format)
HOOK_VAR_FILE3(int, __fprintf_chk, fp, __vfprintf_chk,
HOOK_FILE1(int, puts_unlocked, stdout,
const char *, s)
+/* perror(3) */
+HOOK_VOID1(void, perror, STDERR_FILENO,
+ const char *, s)
+
/* Hook functions which duplicate file descriptors to track them. */
return newfd;
}
-static int (*real_fcntl)(int, int, int);
-int fcntl(int fd, int cmd, int arg) {
+static int (*real_fcntl)(int, int, ...);
+int fcntl(int fd, int cmd, ...) {
int result;
+ va_list ap;
DLSYM_FUNCTION(real_fcntl, "fcntl");
- result = real_fcntl(fd, cmd, arg);
+ /* fcntl() takes different types of arguments depending on the cmd type
+ * (int, void and pointers are used at the moment). Handling these
+ * arguments for different systems and with possible changes in the future
+ * is error prone.
+ *
+ * Therefore always retrieve a void-pointer from our arguments (even if it
+ * wasn't there) and pass it to real_fcntl(). This shouldn't cause any
+ * problems because a void-pointer is most-likely bigger than an int
+ * (something which is not true in reverse) and shouldn't cause
+ * truncation. For register based calling conventions an invalid register
+ * content is passed, but ignored by real_fcntl(). Not perfect, but should
+ * work fine.
+ */
+ va_start(ap, cmd);
+ result = real_fcntl(fd, cmd, va_arg(ap, void *));
+ va_end(ap);
+
/* We only care about duping fds. */
- if (cmd == F_DUPFD) {
+ if (cmd == F_DUPFD && result != -1) {
int saved_errno = errno;
dup_fd(fd, result);
errno = saved_errno;
close_fd(fileno(fp));
return real_fclose(fp);
}
+
+
+/* Hook functions which are necessary for correct tracking. */
+
+#if defined(HAVE_VFORK) && defined(HAVE_FORK)
+pid_t vfork(void) {
+ /* vfork() is similar to fork() but the address space is shared between
+ * father and child. It's designed for fork()/exec() usage because it's
+ * faster than fork(). However according to the POSIX standard the "child"
+ * 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. */
+ 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. */
+
+static int (*real_execve)(const char *filename, char *const argv[], char *const env[]);
+int execve(const char *filename, char *const argv[], char *const env[]) {
+ DLSYM_FUNCTION(real_execve, "execve");
+
+ int found = 0;
+ size_t index = 0;
+
+ /* Count arguments and search for existing ENV_NAME_FDS environment
+ * variable. */
+ 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++;
+ 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
+ * different environment which doesn't include any of our settings. */
+ if (!initialized) {
+ 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);
+
+ 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;
+ }
+
+ return real_execve(filename, argv, env_copy);
+}
+
+#define EXECL_COPY_VARARGS_START(args) \
+ va_list ap; \
+ char *x; \
+ \
+ /* Count arguments. */ \
+ size_t count = 1; /* arg */ \
+ va_start(ap, arg); \
+ while (va_arg(ap, const char *)) { \
+ count++; \
+ } \
+ va_end(ap); \
+ \
+ /* Copy varargs. */ \
+ char *args[count + 1 /* terminating NULL */]; \
+ args[0] = (char *)arg; \
+ \
+ size_t i = 1; \
+ va_start(ap, arg); \
+ while ((x = va_arg(ap, char *))) { \
+ args[i++] = x; \
+ } \
+ args[i] = NULL;
+#define EXECL_COPY_VARARGS_END(args) \
+ va_end(ap);
+#define EXECL_COPY_VARARGS(args) \
+ EXECL_COPY_VARARGS_START(args); \
+ EXECL_COPY_VARARGS_END(args);
+
+int execl(const char *path, const char *arg, ...) {
+ EXECL_COPY_VARARGS(args);
+
+ update_environment();
+ return execv(path, args);
+}
+
+int execlp(const char *file, const char *arg, ...) {
+ EXECL_COPY_VARARGS(args);
+
+ update_environment();
+ return execvp(file, args);
+}
+
+int execle(const char *path, const char *arg, ... /*, char *const envp[] */) {
+ EXECL_COPY_VARARGS_START(args);
+ /* Get envp[] located after arguments. */
+ char * const *envp = va_arg(ap, char * const *);
+ EXECL_COPY_VARARGS_END(args);
+
+ return execve(path, args, envp);
+}
+
+static int (*real_execv)(const char *path, char *const argv[]);
+int execv(const char *path, char *const argv[]) {
+ DLSYM_FUNCTION(real_execv, "execv");
+
+ update_environment();
+ return real_execv(path, argv);
+}
+
+static int (*real_execvp)(const char *path, char *const argv[]);
+int execvp(const char *path, char *const argv[]) {
+ DLSYM_FUNCTION(real_execvp, "execvp");
+
+ update_environment();
+ return real_execvp(path, argv);
+}
ruderich.org/simon / coloredstderr / coloredstderr.git / blobdiff