osc7: initial patch implementation (#154)

* osc7: initial patch implementation

Closes #153

* osc7: avoid redundant use of realpath()

* osc7: fix styling

* Changing position of the OSC7_PATCH toggle in patches.def.h

---------

Co-authored-by: Bakkeby <bakkeby@gmail.com>

patch/newterm.c

@@ -1,7 +1,15 @@
+extern char* argv0;
+
+static char*
+getcwd_by_pid(pid_t pid) {
+	static char cwd[32];
+	snprintf(cwd, sizeof cwd, "/proc/%d/cwd", pid);
+	return cwd;
+}
+
 void
 newterm(const Arg* a)
 {
-	int res;
 	switch (fork()) {
 	case -1:
 		die("fork failed: %s\n", strerror(errno));
@@ -12,19 +20,27 @@ newterm(const Arg* a)
 			die("fork failed: %s\n", strerror(errno));
 			break;
 		case 0:
-			res = chdir(getcwd_by_pid(pid));
-			execlp("st", "./st", NULL);
-			break;
+			#if OSC7_PATCH
+			if (term.cwd) {
+				if (chdir(term.cwd) == 0) {
+					/* We need to put the working directory also in PWD, so that
+					* the shell starts in the right directory if `cwd` is a
+					* symlink. */
+					setenv("PWD", term.cwd, 1);
+				}
+			} else {
+				chdir(getcwd_by_pid(pid));
+			}
+			#else
+			chdir(getcwd_by_pid(pid));
+			#endif // OSC7_PATCH
+
+			execl("/proc/self/exe", argv0, NULL);
+			exit(1);
 		default:
 			exit(0);
 		}
 	default:
 		wait(NULL);
 	}
 }
-
-static char *getcwd_by_pid(pid_t pid) {
-	char buf[32];
-	snprintf(buf, sizeof buf, "/proc/%d/cwd", pid);
-	return realpath(buf, NULL);
-}

patch/newterm.h

@@ -1,2 +1 @@
 void newterm(const Arg *);
-static char *getcwd_by_pid(pid_t pid);

patch/osc7.c

@@ -0,0 +1,74 @@
+static int
+hex2int(char c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	else if (c >= 'a' && c <= 'f')
+		return c - 'a' + 10;
+	else if (c >= 'A' && c <= 'F')
+		return c - 'A' + 10;
+	else
+		return -1;
+}
+
+int
+osc7parsecwd(const char *uri)
+{
+	const char *auth, *host, *hostend;
+	char *path, decoded[PATH_MAX], thishost[_POSIX_HOST_NAME_MAX];
+	size_t i, decodedlen, hostlen, urilen;
+	int h1, h2;
+	if (!term.cwd) {
+		term.cwd = xmalloc(sizeof(decoded));
+		term.cwd[0] = '\0';
+	}
+	/* reset cwd if uri is empty */
+	if ((urilen = strlen(uri)) == 0) {
+		term.cwd[0] = '\0';
+		return 1;
+	}
+	/* decode uri */
+	for (decodedlen = 0, i = 0; i < urilen; i++) {
+		if (uri[i] == '%' && i <= urilen-3 &&
+		    (h1 = hex2int(uri[i+1])) >= 0 && (h2 = hex2int(uri[i+2])) >= 0) {
+			decoded[decodedlen++] = (h1 << 4) | h2;
+			i += 2;
+		} else {
+			decoded[decodedlen++] = uri[i];
+		}
+		if (decodedlen == sizeof(decoded)) {
+			fprintf(stderr, "erresc (OSC 7): uri is too long\n");
+			return 0;
+		}
+	}
+	decoded[decodedlen] = '\0';
+	/* check scheme */
+	if (decodedlen < 5 || strncmp("file:", decoded, 5) != 0) {
+		fprintf(stderr, "erresc (OSC 7): scheme is not supported: '%s'\n", uri);
+		return 0;
+	}
+	/* find start of authority */
+	if (decodedlen < 7 || decoded[5] != '/' || decoded[6] != '/') {
+		fprintf(stderr, "erresc (OSC 7): invalid uri: '%s'\n", uri);
+		return 0;
+	}
+	auth = decoded + 7;
+	/* find start of path and reset cwd if path is missing */
+	if ((path = strchr(auth, '/')) == NULL) {
+		term.cwd[0] = '\0';
+		return 1;
+	}
+	/* ignore path if host is not localhost */
+	host = ((host = memchr(auth, '@', path - auth)) != NULL) ? host+1 : auth;
+	hostend = ((hostend = memchr(host, ':', path - host)) != NULL) ? hostend : path;
+	hostlen = hostend - host;
+	if (gethostname(thishost, sizeof(thishost)) < 0)
+		thishost[0] = '\0';
+	if (hostlen > 0 &&
+	    !(hostlen == 9 && strncmp("localhost", host, hostlen) == 0) &&
+	    !(hostlen == strlen(thishost) && strncmp(host, thishost, hostlen) == 0)) {
+		return 0;
+	}
+	memcpy(term.cwd, path, decodedlen - (path - decoded) + 1);
+	return 1;
+}

patch/osc7.h

@@ -0,0 +1 @@
+static int osc7parsecwd(const char *);

patch/st_include.c

@@ -27,3 +27,6 @@
 #if SYNC_PATCH
 #include "sync.c"
 #endif
+#if OSC7_PATCH
+#include "osc7.c"
+#endif

patch/st_include.h

@@ -30,3 +30,6 @@
 #if SYNC_PATCH
 #include "sync.h"
 #endif
+#if OSC7_PATCH
+#include "osc7.h"
+#endif

patches.def.h

@@ -301,6 +301,14 @@
  */
 #define OPENURLONCLICK_PATCH 0
 
+/* This patch allows st to fetch the current working directory through the OSC 7 escape
+ * sequence emitted by shells. Must be used with newterm patch.
+ *
+ * https://codeberg.org/dnkl/foot/wiki#spawning-new-terminal-instances-in-the-current-working-directory
+ * https://github.com/veltza/st-sx/commit/817865c2c6ed905af8849580e58bdcf399216fbd
+ */
+#define OSC7_PATCH 0
+
 /* This patch allows jumping between prompts by utilizing the OSC 133 escape sequence
  * emitted by shells. Must be used with either reflow or scrollback patch.
  *

st.c

@@ -2654,6 +2654,11 @@ strhandle(void)
 				}
 			}
 			return;
+		#if OSC7_PATCH
+		case 7:
+			osc7parsecwd((const char *)strescseq.args[1]);
+			return;
+		#endif // OSC7_PATCH
 		case 8: /* Clear Hyperlinks */
 			return;
 		case 10:
@@ -2856,6 +2861,19 @@ strparse(void)
 	if (*p == '\0')
 		return;
 
+	/* preserve semicolons in window titles, icon names and OSC 7 sequences */
+	if (strescseq.type == ']' && (
+		p[0] <= '2'
+	#if OSC7_PATCH
+		|| p[0] == '7'
+	#endif // OSC7_PATCH
+	) && p[1] == ';') {
+		strescseq.args[strescseq.narg++] = p;
+		strescseq.args[strescseq.narg++] = p + 2;
+		p[1] = '\0';
+		return;
+	}
+
 	while (strescseq.narg < STR_ARG_SIZ) {
 		strescseq.args[strescseq.narg++] = p;
 		while ((c = *p) != ';' && c != '\0')

st.h

@@ -205,6 +205,9 @@ typedef struct {
 	ImageList *images_alt; /* sixel images for alternate screen */
 	#endif // SIXEL_PATCH
 	Rune lastc;   /* last printed char outside of sequence, 0 if control */
+	#if OSC7_PATCH
+	char* cwd;    /* current working directory */
+	#endif // OSC7_PATCH
 } Term;
 
 typedef union {