Enhance src/consoles.c and src/consoles.h to reflect latest

linux kernel possiblities to detect the devices used for
the system console /dev/console

src/consoles.c

@@ -27,9 +27,23 @@
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/ioctl.h>
+#ifdef __linux__
+# ifndef TIOCGDEV
+#  include <sys/vt.h>
+#  include <sys/kd.h>
+#  include <linux/serial.h>
+# endif
+#endif
+#include <fcntl.h>
 #include <dirent.h>
+#include <unistd.h>
 #include "consoles.h"
 
+#ifdef __linux__
+# include <linux/major.h>
+#endif
+
 #if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
 # ifndef  typeof
 #  define typeof		__typeof__
@@ -43,8 +57,93 @@
 
 struct console *consoles;
 
+/*
+ * Read and allocate one line from file,
+ * the caller has to free the result
+ */
+static
+#ifdef __GNUC__
+__attribute__((__nonnull__))
+#endif
+char *oneline(const char *file)
+{
+	FILE *fp;
+	char *ret = (char*)0, *nl;
+	size_t len = 0;
+
+	if ((fp = fopen(file, "re")) == (FILE*)0)
+		goto err;
+	if (getline(&ret, &len, fp) < 0)
+		goto out;
+	if (len)
+		ret[len-1] = '\0';
+	if ((nl = strchr(ret, '\n')))
+		*nl = '\0';
+out:
+	fclose(fp);
+err:
+	return ret;
+}
+
+#ifdef __linux__
+/*
+ *  Read and determine active attribute for tty,
+ *  the caller has to free the result.
+ */
+static
+__attribute__((__malloc__))
+char *actattr(const char *tty)
+{
+	char *ret = (char*)0;
+	char *path;
+
+	if (!tty || *tty == '\0')
+		goto err;
+
+	if (asprintf(&path, "/sys/class/tty/%s/active", tty) < 0)
+		goto err;
+
+	if ((ret = oneline(path)) == (char*)0)
+		goto out;
+out:
+	free(path);
+err:
+	return ret;
+}
+
+/* Read and determine device attribute for tty */
+static
+dev_t devattr(const char *tty)
+{
+	unsigned int maj, min;
+	dev_t dev = 0;
+	char *path, *value;
+
+	if (!tty || *tty == '\0')
+		goto err;
+
+	if (asprintf(&path, "/sys/class/tty/%s/dev", tty) < 0)
+		goto err;
+
+	if ((value = oneline(path)) == (char*)0)
+		goto out;
+
+	if (sscanf(value, "%u:%u", &maj, &min) == 2)
+		dev = makedev(maj, min);
+	free(value);
+out:
+	free(path);
+err:
+	return dev;
+}
+#endif /* __linux__ */
+
 static dev_t comparedev;
-static char* scandev(DIR *dir)
+static
+#ifdef __GNUC__
+__attribute__((__nonnull__,__malloc__,__hot__))
+#endif
+char* scandev(DIR *dir)
 {
 	char *name = (char*)0;
 	struct dirent *dent;
@@ -69,27 +168,23 @@ static char* scandev(DIR *dir)
 	return name;
 }
 
-void detect_consoles(void)
+static
+struct chardata initcp = {
+	CERASE,
+	CKILL,
+	CTRL('r'),
+	0
+};
+
+static int concount;		/* Counter for console IDs */
+
+static
+#ifdef __GNUC__
+__attribute__((__nonnull__,__hot__))
+#endif
+void consalloc(char * name)
 {
-	FILE *fc;
-	if ((fc = fopen("/proc/consoles", "r"))) {
-		char fbuf[16];
-		int maj, min;
-		DIR *dir;
-		dir = opendir("/dev");
-		if (!dir)
-			goto out;
-		while ((fscanf(fc, "%*s %*s (%[^)]) %d:%d", &fbuf[0], &maj, &min) == 3)) {
 	struct console *restrict tail;
-			char * name;
-
-			if (!strchr(fbuf, 'E'))
-				continue;
-			comparedev = makedev(maj, min);
-			name = scandev(dir);
-
-			if (!name)
-				continue;
 
 	if (posix_memalign((void*)&tail, sizeof(void*), alignof(typeof(struct console))) != 0)
 		perror("memory allocation");
@@ -97,13 +192,208 @@ void detect_consoles(void)
 	tail->next = (struct console*)0;
 	tail->tty = name;
 
+	tail->file = (FILE*)0;
+	tail->flags = 0;
+	tail->fd = -1;
+	tail->id = concount++;
+	tail->pid = 0;
+	memset(&tail->tio, 0, sizeof(tail->tio));
+	memcpy(&tail->cp, &initcp, sizeof(struct chardata));
+
 	if (!consoles)
 		consoles = tail;
 	else
 		consoles->next = tail;
+}
+
+void detect_consoles(const char *console, int fallback)
+{
+#ifdef __linux__
+	char *attrib, *cmdline;
+	FILE *fc;
+
+	if ((fc = fopen("/proc/consoles", "re"))) {
+		char fbuf[16];
+		int maj, min;
+		DIR *dir;
+		dir = opendir("/dev");
+		if (!dir)
+			goto out1;
+		while ((fscanf(fc, "%*s %*s (%[^)]) %d:%d", &fbuf[0], &maj, &min) == 3)) {
+			char * name;
+
+			if (!strchr(fbuf, 'E'))
+				continue;
+			comparedev = makedev(maj, min);
+
+			name = scandev(dir);
+			if (!name)
+				continue;
+			consalloc(name);
 		}
 		closedir(dir);
-out:
+out1:
 		fclose(fc);
+		return;
+	}
+
+	if ((attrib = actattr("console"))) {
+		char *words = attrib, *token;
+		DIR *dir;
+
+		dir = opendir("/dev");
+		if (!dir)
+			goto out2;
+		while ((token = strsep(&words, " \t\r\n"))) {
+			char * name;
+
+			if (*token == '\0')
+				continue;
+			comparedev = devattr(token);
+			if (comparedev == makedev(TTY_MAJOR, 0)) {
+				char *tmp = actattr(token);
+				if (!tmp)
+					continue;
+				comparedev = devattr(tmp);
+				free(tmp);
+			}
+
+			name = scandev(dir);
+			if (!name)
+				continue;
+			consalloc(name);
+		}
+		closedir(dir);
+out2:
+		free(attrib);
+		return;
+
+	}
+
+	if ((cmdline = oneline("/proc/cmdline"))) {
+		char *words= cmdline, *token;
+		DIR *dir;
+
+		dir = opendir("/dev");
+		if (!dir)
+			goto out3;
+		while ((token = strsep(&words, " \t\r\n"))) {
+#ifdef TIOCGDEV
+			unsigned int devnum;
+#else
+			struct vt_stat vt;
+			struct stat st;
+#endif
+			char *colon, *name;
+			int fd;
+
+			if (*token != 'c')
+				continue;
+
+			if (strncmp(token, "console=", 8) != 0)
+				continue;
+			token += 8;
+
+			if (strcmp(token, "brl") == 0)
+				token += 4;
+			if ((colon = strchr(token, ',')))
+				*colon = '\0';
+
+			if (asprintf(&name, "/dev/%s", token) < 0)
+				continue;
+
+			if ((fd = open(name, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC)) < 0) {
+				free(name);
+				continue;
+			}
+			free(name);
+#ifdef TIOCGDEV
+			if (ioctl (fd, TIOCGDEV, &devnum) < 0) {
+				close(fd);
+				continue;
+			}
+			comparedev = (dev_t)devnum;
+#else
+			if (fstat(fd, &st) < 0) {
+				close(fd);
+				continue;
+			}
+			comparedev = st.st_rdev;
+			if (comparedev == makedev(TTY_MAJOR, 0)) {
+				if (ioctl(fd, VT_GETSTATE, &vt) < 0) {
+					close(fd);
+					continue;
+				}
+				comparedev = makedev(TTY_MAJOR, (int)vt.v_active);
+			}
+#endif
+			close(fd);
+
+			name = scandev(dir);
+			if (!name)
+				continue;
+			consalloc(name);
+		}
+		closedir(dir);
+out3:
+		free(cmdline);
+		return;
+	}
+#endif /* __linux __ */
+	if (console && *console) {
+		int fd;
+		DIR *dir;
+		char *name;
+#ifdef TIOCGDEV
+		unsigned int devnum;
+#else
+# ifdef __linux__
+		struct vt_stat vt;
+# endif
+		struct stat st;
+#endif
+
+		if ((fd = open(console, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC)) < 0)
+			return;
+#ifdef TIOCGDEV
+		if (ioctl (fd, TIOCGDEV, &devnum) < 0) {
+			close(fd);
+			return;
+		}
+		comparedev = (dev_t)devnum;
+#else
+		if (fstat(fd, &st) < 0) {
+			close(fd);
+			return;
+		}
+# ifdef __linux__
+		comparedev = st.st_rdev;
+		if (comparedev == makedev(TTY_MAJOR, 0)) {
+			if (ioctl(fd, VT_GETSTATE, &vt) < 0) {
+				close(fd);
+				return;
+			}
+			comparedev = makedev(TTY_MAJOR, (int)vt.v_active);
+		}
+# endif
+#endif
+		close(fd);
+		dir = opendir("/dev");
+		if (!dir)
+			return;
+		name = scandev(dir);
+		if (name)
+			consalloc(name);
+		closedir(dir);
+		return;
+	}
+
+	if (fallback >= 0) {
+		const char *name = ttyname(fallback);
+		if (!name)
+			name = "/dev/console";
+		consalloc(strdup(name));
+		if (consoles)
+			consoles->fd = fallback;
 	}
 }

src/consoles.h

@@ -21,13 +21,28 @@
  * Author: Werner Fink <werner@suse.de>
  */
 
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdio.h>
 #include <termios.h>
 
+struct chardata {
+	uint8_t	erase;
+	uint8_t kill;
+	uint8_t eol;
+	uint8_t parity;
+};
 struct console {
-	char * tty;
+	char *tty;
-	int tlock;
+	FILE *file;
-	struct termios ltio, otio;
+	uint32_t flags;
+	int fd, id;
+#define	CON_SERIAL	0x0001
+#define	CON_NOTTY	0x0002
+	pid_t pid;
+	struct chardata cp;
+	struct termios tio;
 	struct console *next;
 };
 extern struct console *consoles;
-extern void detect_consoles(void);
+extern void detect_consoles(const char *console, int fallback);