Attempt to log distro name/version in Unix crashlog.

Factor out fork/execve/read stdout code into own function.

src/crashlog.cpp

@@ -69,6 +69,12 @@ char *CrashLog::LogCompiler(char *buffer, const char *last) const
 #endif
 }
 
+/* virtual */ char *CrashLog::LogOSVersionDetail(char *buffer, const char *last) const
+{
+	/* Stub implementation; not all OSes support this. */
+	return buffer;
+}
+
 /* virtual */ char *CrashLog::LogRegisters(char *buffer, const char *last) const
 {
 	/* Stub implementation; not all OSes support this. */
@@ -350,6 +356,7 @@ char *CrashLog::FillCrashLog(char *buffer, const char *last) const
 	buffer = this->LogRegisters(buffer, last);
 	buffer = this->LogOSVersion(buffer, last);
 	buffer = this->LogCompiler(buffer, last);
+	buffer = this->LogOSVersionDetail(buffer, last);
 	buffer = this->LogConfiguration(buffer, last);
 	buffer = this->LogLibraries(buffer, last);
 	buffer = this->LogModules(buffer, last);

src/crashlog.h

@@ -44,6 +44,14 @@ protected:
 	 */
 	virtual char *LogCompiler(char *buffer, const char *last) const;
 
+	/**
+	 * Writes OS' version detail to the buffer, if available.
+	 * @param buffer The begin where to write at.
+	 * @param last   The last position in the buffer to write to.
+	 * @return the position of the \c '\0' character after the buffer.
+	 */
+	virtual char *LogOSVersionDetail(char *buffer, const char *last) const;
+
 	/**
 	 * Writes actually encountered error to the buffer.
 	 * @param buffer  The begin where to write at.

src/os/unix/crashlog_unix.cpp

@@ -20,14 +20,13 @@
 #include <signal.h>
 #include <sys/utsname.h>
 #include <setjmp.h>
-
-#if defined(WITH_DBG_GDB)
 #include <unistd.h>
-#include <sys/stat.h>
 #include <fcntl.h>
-#include <sys/syscall.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+
+#if defined(WITH_DBG_GDB)
+#include <sys/syscall.h>
 #endif /* WITH_DBG_GDB */
 
 #if defined(WITH_PRCTL_PT)
@@ -74,6 +73,60 @@ static void LogStacktraceSigSegvHandler(int  sig)
 }
 #endif
 
+static bool ExecReadStdout(const char *file, char *const *args, char *&buffer, const char *last)
+{
+	int pipefd[2];
+	if (pipe(pipefd) == -1) return false;
+
+	int pid = fork();
+	if (pid < 0) return false;
+
+	if (pid == 0) {
+		/* child */
+
+		close(pipefd[0]); /* Close unused read end */
+		dup2(pipefd[1], STDOUT_FILENO);
+		close(pipefd[1]);
+		int null_fd = open("/dev/null", O_RDWR);
+		if (null_fd != -1) {
+			dup2(null_fd, STDERR_FILENO);
+			dup2(null_fd, STDIN_FILENO);
+		}
+
+		execvp(file, args);
+		exit(42);
+	}
+
+	/* parent */
+
+	close(pipefd[1]); /* Close unused write end */
+
+	while (buffer < last) {
+		ssize_t res = read(pipefd[0], buffer, last - buffer);
+		if (res < 0) {
+			if (errno == EINTR) continue;
+			break;
+		} else if (res == 0) {
+			break;
+		} else {
+			buffer += res;
+		}
+	}
+	buffer += seprintf(buffer, last, "\n");
+
+	close(pipefd[0]); /* close read end */
+
+	int status;
+	int wait_ret = waitpid(pid, &status, 0);
+	if (wait_ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+		/* command did not appear to run successfully */
+		return false;
+	} else {
+		/* command executed successfully */
+		return true;
+	}
+}
+
 /**
  * Unix implementation for the crash logger.
  */
@@ -107,6 +160,23 @@ class CrashLogUnix : public CrashLog {
 		);
 	}
 
+	/* virtual */ char *LogOSVersionDetail(char *buffer, const char *last) const
+	{
+		struct utsname name;
+		if (uname(&name) < 0) return buffer;
+
+		if (strcmp(name.sysname, "Linux") == 0) {
+			char *buffer_orig = buffer;
+			buffer += seprintf(buffer, last, "Distro version:\n");
+
+			const char *args[] = { "/bin/sh", "-c", "lsb_release -a || find /etc -maxdepth 1 -type f -a \\( -name '*release' -o -name '*version' \\) -exec head -v {} \\+", NULL };
+			if (!ExecReadStdout("/bin/sh", const_cast<char* const*>(args), buffer, last)) {
+				buffer = buffer_orig;
+			}
+		}
+		return buffer;
+	}
+
 	/* virtual */ char *LogError(char *buffer, const char *last, const char *message) const
 	{
 		buffer += seprintf(buffer, last,
@@ -253,23 +323,8 @@ class CrashLogUnix : public CrashLog {
 
 		pid_t tid = syscall(SYS_gettid);
 
-		int pipefd[2];
+		char *buffer_orig = buffer;
-		if (pipe(pipefd) == -1) return buffer;
+		buffer += seprintf(buffer, last, "GDB info:\n");
-
-		int pid = fork();
-		if (pid < 0) return buffer;
-
-		if (pid == 0) {
-			/* child */
-
-			close(pipefd[0]); /* Close unused read end */
-			dup2(pipefd[1], STDOUT_FILENO);
-			close(pipefd[1]);
-			int null_fd = open("/dev/null", O_RDWR);
-			if (null_fd != -1) {
-				dup2(null_fd, STDERR_FILENO);
-				dup2(null_fd, STDIN_FILENO);
-			}
 
 		char tid_buffer[16];
 		char disasm_buffer[32];
@@ -301,36 +356,7 @@ class CrashLogUnix : public CrashLog {
 #endif
 
 		args.push_back(NULL);
-			execvp("gdb", const_cast<char* const*>(&(args[0])));
+		if (!ExecReadStdout("gdb", const_cast<char* const*>(&(args[0])), buffer, last)) {
-			exit(42);
-		}
-
-		/* parent */
-
-		close(pipefd[1]); /* Close unused write end */
-
-		char *buffer_orig = buffer;
-
-		buffer += seprintf(buffer, last, "GDB info:\n");
-		while (buffer < last) {
-			ssize_t res = read(pipefd[0], buffer, last - buffer);
-			if (res < 0) {
-				if (errno == EINTR) continue;
-				break;
-			} else if (res == 0) {
-				break;
-			} else {
-				buffer += res;
-			}
-		}
-		buffer += seprintf(buffer, last, "\n");
-
-		close(pipefd[0]); /* close read end */
-
-		int status;
-		int wait_ret = waitpid(pid, &status, 0);
-		if (wait_ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
-			/* gdb did not appear to run successfully */
 			buffer = buffer_orig;
 		}
 #endif /* WITH_DBG_GDB */