Michael Brown
2009-Feb-16 08:49 UTC
[syslinux] [PATCH] cmd.c32: new module to just execute a command
Trivial module to execute an arbitrary command.
---
com32/modules/Makefile | 2 +-
com32/modules/cmd.c | 42 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+), 1 deletions(-)
create mode 100644 com32/modules/cmd.c
diff --git a/com32/modules/Makefile b/com32/modules/Makefile
index 2739a39..930e89b 100644
--- a/com32/modules/Makefile
+++ b/com32/modules/Makefile
@@ -20,7 +20,7 @@ include ../MCONFIG
MODULES = chain.c32 config.c32 ethersel.c32 mboot.c32 dmitest.c32 \
cpuidtest.c32 \
pcitest.c32 elf.c32 linux.c32 reboot.c32 pmload.c32 meminfo.c32 \
- sdi.c32 sanboot.c32 ifcpu64.c32 vesainfo.c32 kbdmap.c32
+ sdi.c32 sanboot.c32 ifcpu64.c32 vesainfo.c32 kbdmap.c32 cmd.c32
TESTFILES
diff --git a/com32/modules/cmd.c b/com32/modules/cmd.c
new file mode 100644
index 0000000..f0b0a96
--- /dev/null
+++ b/com32/modules/cmd.c
@@ -0,0 +1,42 @@
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2008 Michael Brown - All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston MA 02110-1301, USA; either version 2 of the License, or
+ * (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * cmd.c
+ *
+ * Execute arbitrary commands
+ */
+
+#include <string.h>
+#include <alloca.h>
+#include <console.h>
+#include <com32.h>
+
+int main(int argc, const char *argv[])
+{
+ size_t len = 0;
+ char *cmd;
+ char *tmp;
+ int i;
+
+ openconsole(&dev_stdcon_r, &dev_stdcon_w);
+
+ for (i = 1; i < argc; i++)
+ len += strlen(argv[i]) + 1;
+
+ tmp = cmd = alloca(len);
+
+ for (i = 1; i < argc; i++)
+ tmp += sprintf(tmp, "%s%s", argv[i], (i == argc-1) ? ""
: " ");
+
+ syslinux_run_command(cmd);
+}
--
1.5.4.3
Gene Cumm
2009-Feb-16 14:45 UTC
[syslinux] [PATCH] cmd.c32: new module to just execute a command
On Mon, Feb 16, 2009 at 3:49 AM, Michael Brown <mcb30 at etherboot.org> wrote:> Trivial module to execute an arbitrary command.Similar in function to the alias module I created back in October. The key differences I notice are that yours appears simpler, mine could also be tested as a Linux binary, yours uses sprintf versus mine using memcpy and mine would definitely not pass a command string that was too long to syslinux_run_command(). I'm not sure if it's even theoretically possible to even do so though. It's probably an unnecessary but paranoid check. I originally created mine because I often had multiple labels doing similar tasks with either no or minor variations (short name vs long name; main vs add an additional parameter) and there's no way for one label to call another (as far as I could tell). Including something that provides this functionality into Syslinux would probably provide benefit for anyone that has multiple similar labels. -- -Gene "No one ever says, 'I can't read that ASCII E-mail you sent me.'"
Michael Brown
2009-Feb-17 06:15 UTC
[syslinux] [PATCH] cmd.c32: new module to just execute a command
On Monday 16 February 2009 14:45:36 Gene Cumm wrote:> On Mon, Feb 16, 2009 at 3:49 AM, Michael Brown <mcb30 at etherboot.org> wrote: > > Trivial module to execute an arbitrary command. > > Similar in function to the alias module I created back in October. > The key differences I notice are that yours appears simpler, mine > could also be tested as a Linux binary, yours uses sprintf versus mine > using memcpy and mine would definitely not pass a command string that > was too long to syslinux_run_command().Is there an upper limit on the length of command strings? Michael
Sebastian Herbszt
2009-Feb-17 22:03 UTC
[syslinux] [PATCH] cmd.c32: new module to just execute a command
Michael Brown wrote:> On Monday 16 February 2009 14:45:36 Gene Cumm wrote: >> On Mon, Feb 16, 2009 at 3:49 AM, Michael Brown <mcb30 at etherboot.org> wrote: >> > Trivial module to execute an arbitrary command. >> >> Similar in function to the alias module I created back in October. >> The key differences I notice are that yours appears simpler, mine >> could also be tested as a Linux binary, yours uses sprintf versus mine >> using memcpy and mine would definitely not pass a command string that >> was too long to syslinux_run_command(). > > Is there an upper limit on the length of command strings?syslinux_run_command() uses INT 22h AX=0003h (com32/lib/syslinux/run_command.c) which copies the command line from ES:BX to "command_line" (core/comboot.inc). parseconfig.inc:command_line resb max_cmd_len+2 ; Command line buffer config.inc:max_cmd_len equ 2047 ; Must be &3; 2047 is the kernel limit - Sebastian
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