From 199183d5babe50b05ef4b91e2bba390fa2d4bf06 Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Sun, 22 Nov 2009 20:54:00 +0100
Subject: Show command lines in task list

	* Makefile.am (clib_routines): Add memcmp.
	* i386/i386/db_machdep.h (DB_GNUMACH_TASK_NAME): New macro.
	* i386/i386/db_interface.c (GNU): New macro.
	[GNU] (looks_like_command): New function.
	(db_task_name): When task map is kernel_pmap, return
	DB_GNUMACH_TASK_NAME.
	[GNU] (db_task_name): Use a GNU/Hurd-specific heuristic to get
	argv[] of a task.
---
 Makefile.am              |  2 +-
 i386/i386/db_interface.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++
 i386/i386/db_machdep.h   |  1 +
 3 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index d6fbb54..25fd403 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -133,7 +133,7 @@ noinst_PROGRAMS += \
 	gnumach.o
 
 # This is the list of routines we decide is OK to steal from the C library.
-clib_routines := memcpy memmove memset bcopy bzero		\
+clib_routines := memcmp memcpy memmove memset bcopy bzero	\
 		 strchr strstr strsep strpbrk strtok		\
 		 htonl htons ntohl ntohs			\
 		 udivdi3 __udivdi3				\
diff --git a/i386/i386/db_interface.c b/i386/i386/db_interface.c
index be0c893..d149adc 100644
--- a/i386/i386/db_interface.c
+++ b/i386/i386/db_interface.c
@@ -520,6 +520,53 @@ db_search_null(
 	return FALSE;
 }
 
+#define GNU
+
+#ifdef GNU
+static boolean_t
+looks_like_command(
+	task_t		task,
+	char*		kaddr)
+{
+	char *c;
+
+	assert(!((vm_offset_t) kaddr & (INTEL_PGBYTES-1)));
+
+	/*
+	 * Must be the environment.
+	 */
+	if (!memcmp(kaddr, "PATH=", 5) || !memcmp(kaddr, "TERM=", 5) || !memcmp(kaddr, "SHELL=", 6) || !memcmp(kaddr, "LOCAL_PART=", 11) || !memcmp(kaddr, "LC_ALL=", 7))
+		return FALSE;
+
+	/*
+	 * This is purely heuristical but works quite nicely.
+	 * We know that it should look like words separated by \0, and
+	 * eventually only \0s.
+	 */
+	c = kaddr;
+	while (c < kaddr + INTEL_PGBYTES) {
+		if (!*c) {
+			if (c == kaddr)
+				/* Starts by \0.  */
+				return FALSE;
+			break;
+		}
+		while (c < kaddr + INTEL_PGBYTES && *c)
+			c++;
+		if (c < kaddr + INTEL_PGBYTES)
+			c++;	/* Skip \0 */
+	}
+	/*
+	 * Check that the remainder is just \0s.
+	 */
+	while (c < kaddr + INTEL_PGBYTES)
+		if (*c++)
+			return FALSE;
+
+	return TRUE;
+}
+#endif
+
 void
 db_task_name(
 	task_t		task)
@@ -527,7 +574,46 @@ db_task_name(
 	register char *p;
 	register int n;
 	unsigned vaddr, kaddr;
+	unsigned sp;
 
+	if (task->map->pmap == kernel_pmap) {
+		db_printf(DB_GNUMACH_TASK_NAME);
+		return;
+	}
+
+#ifdef GNU
+	/*
+	 * GNU Hurd-specific heuristics.
+	 */
+
+	/* Heuristical address first.  */
+	vaddr = 0x1026000;
+	if (db_user_to_kernel_address(task, vaddr, &kaddr, 0) >= 0 &&
+		looks_like_command(task, (char*) kaddr))
+			goto ok;
+
+	/* Try to catch SP of the main thread.  */
+	thread_t thread;
+
+	task_lock(task);
+	thread = (thread_t) queue_first(&task->thread_list);
+	if (!thread) {
+		task_unlock(task);
+		db_printf(DB_NULL_TASK_NAME);
+		return;
+	}
+	sp = thread->pcb->iss.uesp;
+	task_unlock(task);
+
+	vaddr = (sp & ~(INTEL_PGBYTES - 1)) + INTEL_PGBYTES;
+	while (1) {
+		if (db_user_to_kernel_address(task, vaddr, &kaddr, 0) < 0)
+			return FALSE;
+		if (looks_like_command(task, (char*) kaddr))
+			break;
+		vaddr += INTEL_PGBYTES;
+	}
+#else
 	vaddr = DB_USER_STACK_ADDR;
 	kaddr = 0;
 
@@ -545,11 +631,18 @@ db_task_name(
 	    db_printf(DB_NULL_TASK_NAME);
 	    return;
 	}
+#endif
 
+ok:
 	n = DB_TASK_NAME_LEN-1;
+#ifdef GNU
+	p = (char *)kaddr;
+	for (; n > 0; vaddr++, p++, n--) {
+#else
 	p = (char *)kaddr + sizeof(unsigned);
 	for (vaddr += sizeof(int); vaddr < DB_USER_STACK_ADDR && n > 0;
 							vaddr++, p++, n--) {
+#endif
 	    if (vaddr % INTEL_PGBYTES == 0) {
 		(void)db_user_to_kernel_address(task, vaddr, &kaddr, 0);
 		p = (char*)kaddr;
diff --git a/i386/i386/db_machdep.h b/i386/i386/db_machdep.h
index cba259c..95e3797 100644
--- a/i386/i386/db_machdep.h
+++ b/i386/i386/db_machdep.h
@@ -94,6 +94,7 @@ db_regs_t	ddb_regs;	/* register state */
 #define DB_TASK_NAME_TITLE	"COMMAND                "
 #define DB_TASK_NAME_LEN	23
 #define DB_NULL_TASK_NAME	"?                      "
+#define DB_GNUMACH_TASK_NAME	"gnumach                "
 
 /* macro for checking if a thread has used floating-point */
 
-- 
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