pxe: Allow use of environment variables in append string

PATCH New Hans de Goede 2 participants 3 messages Aug 1, 2014 – Aug 4, 2014

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Hans de Goede

author

2014-08-01 09:21 UTC #0 lore raw

PATCH 1/1 pxe: Allow use of environment variables in append string

Use run_command("setenv bootargs <label->append>") so that environment variables (e.g. $console) can be used in append strings.

Signed-off-by Hans de Goede <[email protected]>

---
 common/cmd_pxe.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

common/cmd_pxe.c +16 -7

index ba48692..3866604 100644
@@ -571,14 +571,23 @@ static void label_print(void *data)
 static int label_localboot(struct pxe_label *label)
 {
 	char *localcmd;
+	char *bootargs;
 
 	localcmd = from_env("localcmd");
 
 	if (!localcmd)
 		return -ENOENT;
 
-	if (label->append)
-		setenv("bootargs", label->append);
+	if (label->append) {
+		bootargs = malloc(strlen("setenv bootargs ") +
+				  strlen(label->append) + 1);
+		if (!bootargs)
+			return 1;
+		strcpy(bootargs, "setenv bootargs ");
+		strcat(bootargs, label->append);
+		run_command(bootargs, 0);
+		free(bootargs);
+	}
 
 	debug("running: %s\n", localcmd);

@@ -669,17 +678,17 @@ static int label_boot(cmd_tbl_t *cmdtp, struct pxe_label *label)
 		len += strlen(label->append);
 
 	if (len) {
-		bootargs = malloc(len + 1);
+		bootargs = malloc(strlen("setenv bootargs ") + len + 1);
 		if (!bootargs)
 			return 1;
-		bootargs[0] = '\0';
+		strcpy(bootargs, "setenv bootargs ");
 		if (label->append)
-			strcpy(bootargs, label->append);
+			strcat(bootargs, label->append);
 		strcat(bootargs, ip_str);
 		strcat(bootargs, mac_str);
 
-		setenv("bootargs", bootargs);
-		printf("append: %s\n", bootargs);
+		run_command(bootargs, 0);
+		printf("append: %s\n", getenv("bootargs"));
 
 		free(bootargs);
 	}

Signature · 1 line

2.0.3

Stephen Warren

2014-08-01 19:07 UTC #1 lore raw

PATCH 1/1 pxe: Allow use of environment variables in append string

Quoted 2 lines · Hans de Goede

Use run_command("setenv bootargs <label->append>") so that environment variables (e.g. $console) can be used in append strings.

I'm slightly worried that this changes the semantics of the append line in the PXE/extlinux config file. Namely, you suddenly have to start worrying about escaping any $ signs or semi-colons etc..

common/cmd_pxe.c static void label_print(void *data) · line 585

Quoted 12 lines

common/cmd_pxe.c +5 -2

 
  	if (!localcmd)
  		return -ENOENT;
 
-	if (label->append)
-		setenv("bootargs", label->append);
+	if (label->append) {
+		bootargs = malloc(strlen("setenv bootargs ") +
+				  strlen(label->append) + 1);
+		if (!bootargs)
+			return 1;

Shouldn't this return a -ve error code for consistency with the other pre-existing error case I quoted above.

common/cmd_pxe.c static void label_print(void *data) · line 588

Quoted 3 lines

common/cmd_pxe.c +3 -0

+		strcpy(bootargs, "setenv bootargs ");
+		strcat(bootargs, label->append);
+		run_command(bootargs, 0);

Using whatever C function that the shell uses to expand variable references in the command-line, rather than run_command(), would at least avoid the issue of ; in label->append causing part of label->append after the ; to be execututed as a separate command.

There would still be the issue of $ suddenly meaning something different.

Hans de Goede

author

2014-08-04 18:29 UTC #2 lore raw

PATCH 1/1 pxe: Allow use of environment variables in append string

Hi,

Quoted 5 lines · Stephen Warren

Quoted 2 lines · Hans de Goede
Use run_command("setenv bootargs <label->append>") so that environment variables (e.g. $console) can be used in append strings.
I'm slightly worried that this changes the semantics of the append line in the PXE/extlinux config file. Namely, you suddenly have to start worrying about escaping any $ signs or semi-colons etc..

I'm not that worried about $ needing escaping, as I cannot think of any kernel commandline options using $, maybe they exist but if they do they are quite rare.

But you make a good point about the ; I know some kernel cmdline options which use those...

Quoted 14 lines

common/cmd_pxe.c static void label_print(void *data) · line 585

Quoted 13 lines

common/cmd_pxe.c +5 -2

 
      if (!localcmd)
          return -ENOENT;
 
-    if (label->append)
-        setenv("bootargs", label->append);
+    if (label->append) {
+        bootargs = malloc(strlen("setenv bootargs ") +
+                  strlen(label->append) + 1);
+        if (!bootargs)
+            return 1;

Quoted 1 line

Shouldn't this return a -ve error code for consistency with the other pre-existing error case I quoted above.

Yeah this is weird, I copy pasted this from
the label_boot() function, of which is a special version, also label_boot() is the only caller of label_localboot() (where this hunk applies), and it does not check the return value at all...

I could make it -ENOMEM if you prefer.

Quoted 5 lines

common/cmd_pxe.c static void label_print(void *data) · line 588
Quoted 3 lines
common/cmd_pxe.c +3 -0
+        strcpy(bootargs, "setenv bootargs ");
+        strcat(bootargs, label->append);
+        run_command(bootargs, 0);
Using whatever C function that the shell uses to expand variable references in the command-line, rather than run_command(), would at least avoid the issue of ; in label->append causing part of label->append after the ; to be execututed as a separate command.

Ack, I'll look into that and post a v2 with that change.

Quoted 1 line

There would still be the issue of $ suddenly meaning something different.

Right, but as said I'm not really worried about that.

Regards,

Hans