RunApp: safer chdir. Overhauled "sparn a child and get its output" in general

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

4 files changed, 128 insertions, 31 deletions

diff --git a/lib/Utils/Makefile.am b/lib/Utils/Makefile.am
index d5e9d98..a944d97 100644
--- a/lib/Utils/Makefile.am
+++ b/lib/Utils/Makefile.am
@@ -16,7 +16,7 @@ libABRTUtils_la_SOURCES = \
     daemon.cpp \
     skip_whitespace.cpp \
     xatonum.cpp \
-    popen_and_save_output.cpp \
+    spawn.cpp \
     stringops.cpp \
     dirsize.cpp \
     DebugDump.h DebugDump.cpp \
diff --git a/lib/Utils/popen_and_save_output.cpp b/lib/Utils/popen_and_save_output.cpp
deleted file mode 100644
index 4bcbcac..0000000
--- a/lib/Utils/popen_and_save_output.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-/*
- * Utility routines.
- *
- * Licensed under GPLv2 or later, see file COPYING in this tarball for details.
- */
-#include "abrtlib.h"
-
-using namespace std;
-
-string popen_and_save_output(const char *cmd)
-{
-    string result;
-
-    FILE *fp = popen(cmd, "r");
-    if (fp == NULL) /* fork or pipe failed; or out-of-mem */
-    {
-        return result;
-    }
-
-    size_t sz;
-    char buf[BUFSIZ + 1];
-    while ((sz = fread(buf, 1, sizeof(buf)-1, fp)) > 0)
-    {
-        buf[sz] = '\0';
-        result += buf;
-    }
-    pclose(fp);
-
-    return result;
-}
diff --git a/lib/Utils/spawn.cpp b/lib/Utils/spawn.cpp
new file mode 100644
index 0000000..4b0eecb
--- /dev/null
+++ b/lib/Utils/spawn.cpp
@@ -0,0 +1,121 @@
+/*
+ * Utility routines.
+ *
+ * Licensed under GPLv2, see file COPYING in this tarball for details.
+ */
+#include "abrtlib.h"
+
+/* Returns pid */
+pid_t fork_execv_on_steroids(int flags,
+		char **argv,
+		int *pipefds,
+		char **unsetenv_vec,
+		const char *dir,
+		uid_t uid)
+{
+	pid_t child;
+	/* Reminder: [0] is read end, [1] is write end */
+	int pipe_to_child[2];
+	int pipe_fm_child[2];
+
+	/* Sanitize flags */
+	if (!pipefds)
+		flags &= ~(EXECFLG_INPUT | EXECFLG_OUTPUT);
+
+	if (flags & EXECFLG_INPUT)
+		xpipe(pipe_to_child);
+	if (flags & EXECFLG_OUTPUT)
+		xpipe(pipe_fm_child);
+
+	child = fork();
+	if (child == -1) {
+		perror_msg_and_die("fork");
+	}
+	if (child == 0) {
+		/* Child */
+
+		/* Play with stdio descriptors */
+		if (flags & EXECFLG_INPUT) {
+			xmove_fd(pipe_to_child[0], STDIN_FILENO);
+		} else if (flags & EXECFLG_INPUT_NUL) {
+			xmove_fd(xopen("/dev/null", O_RDWR), STDIN_FILENO);
+		}
+		if (flags & EXECFLG_OUTPUT) {
+			xmove_fd(pipe_fm_child[1], STDOUT_FILENO);
+		} else if (flags & EXECFLG_OUTPUT_NUL) {
+			xmove_fd(xopen("/dev/null", O_RDWR), STDOUT_FILENO);
+		}
+		if (flags & EXECFLG_ERR2OUT) {
+			/* Want parent to see errors in the same stream */
+			xdup2(STDOUT_FILENO, STDERR_FILENO);
+		} else if (flags & EXECFLG_ERR_NUL) {
+			xmove_fd(xopen("/dev/null", O_RDWR), STDERR_FILENO);
+		}
+
+		if (flags & EXECFLG_SETGUID) {
+			struct passwd* pw = getpwuid(uid);
+			gid_t gid = pw ? pw->pw_gid : uid;
+			setgroups(1, &gid);
+			xsetregid(gid, gid);
+			xsetreuid(uid, uid);
+		}
+		if (flags & EXECFLG_SETSID)
+			setsid();
+
+		if (unsetenv_vec) {
+			while (*unsetenv_vec)
+				unsetenv(*unsetenv_vec++);
+		}
+
+		if (dir)
+			xchdir(dir);
+
+		execvp(argv[0], argv);
+		if (!(flags & EXECFLG_QUIET))
+			perror_msg("Can't execute '%s'", argv[0]);
+		exit(127); /* shell uses this exitcode in this case */
+	}
+
+	if (flags & EXECFLG_INPUT) {
+		close(pipe_to_child[0]);
+		pipefds[1] = pipe_to_child[1];
+	}
+	if (flags & EXECFLG_OUTPUT) {
+		close(pipe_fm_child[1]);
+		pipefds[0] = pipe_fm_child[0];
+	}
+
+	return child;
+}
+
+char *run_in_shell_and_save_output(int flags,
+		const char *cmd,
+		const char *dir,
+		size_t *size_p)
+{
+	flags |= EXECFLG_OUTPUT;
+	flags &= ~EXECFLG_INPUT;
+
+	const char *argv[] = { "/bin/sh", "sh", "-c", cmd, NULL };
+	int pipeout[2];
+	pid_t child = fork_execv_on_steroids(flags, (char **)argv, pipeout,
+		/*unsetenv_vec:*/ NULL, dir, /*uid (unused):*/ 0);
+
+	size_t pos = 0;
+	char *result = NULL;
+	while (1) {
+		result = (char*) xrealloc(result, pos + 4*1024 + 1);
+		size_t sz = safe_read(pipeout[0], result + pos, 4*1024);
+		if (sz <= 0) {
+			break;
+		}
+		pos += sz;
+	}
+	result[pos] = '\0';
+	if (size_p)
+		*size_p = pos;
+	close(pipeout[0]);
+	waitpid(child, NULL, 0);
+
+	return result;
+}
diff --git a/lib/Utils/xfuncs.cpp b/lib/Utils/xfuncs.cpp
index 8621b5f..3ab3739 100644
--- a/lib/Utils/xfuncs.cpp
+++ b/lib/Utils/xfuncs.cpp
@@ -141,6 +141,12 @@ off_t xlseek(int fd, off_t offset, int whence)
 	return off;
 }
 
+void xchdir(const char *path)
+{
+	if (chdir(path))
+		perror_msg_and_die("chdir(%s)", path);
+}
+
 char* xvasprintf(const char *format, va_list p)
 {
 	int r;