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environment: ignore env var assignments > 1 KiB (#2325)

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...to guard against recursive constructs like FOO=$FOO:bar which would
grow on each reconfigure.

Add log message as well as a warning against this in the man page.
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Johan Malm 2024-11-10 20:40:51 +00:00 • committed by GitHub
parent fc774d0071
commit a88c721979
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2 changed files with 33 additions and 3 deletions
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11
docs/labwc-config.5.scd
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@ -50,9 +50,14 @@ that directory contains either the "environment" file or at least one
Note: environment files are treated differently by Openbox, which will simply
source the file as a valid shell script before running the window manager. Files
are instead parsed directly by labwc, although any environment variables
referenced as $VARIABLE or ${VARIABLE} will be substituted and the tilde (~)
will be expanded as the user's home directory.
are instead parsed directly by labwc so that environment variables can be
re-loaded on --reconfigure.
Any environment variables referenced as $VARIABLE or ${VARIABLE} will be
substituted and the tilde (~) will be expanded as the user's home directory.
Please note that as labwc reloads the environment file(s) on reconfigure,
recursive/circular assignments (for example FOO=$FOO:bar) should not be made.
The *autostart* file is executed as a shell script after labwc has read its
configuration and set variables defined in the environment file. Additionally,

25
src/config/session.c
View file

@ -33,6 +33,7 @@ static const char *const env_vars[] = {
NULL
};
#define LAB_ENV_VAR_MAX_SIZE 1024
static void
process_line(char *line)
{
@ -52,12 +53,36 @@ process_line(char *line)
struct buf value = BUF_INIT;
buf_add(&value, string_strip(++p));
/*
* Users should not assign environment variables recursively (for
* example FOO=$FOO:bar) in the environment file because they would just
* keep growing on reconfigure. We could of course try to remember the
* original values, but it adds complexity for which we currently cannot
* see a use-case that could not easily be handled by some shell scripts
* separate from the environment file.
*
* Consequently we just check the size of the environment variables to
* defensively handle that growth issue in the case of inadvertent
* recursion.
*/
if (value.len > LAB_ENV_VAR_MAX_SIZE) {
wlr_log(WLR_ERROR, "ignoring environment variable assignment as "
"its size is greater than %d bytes which indicates recursion "
"(%s=%s)", LAB_ENV_VAR_MAX_SIZE, key, value.data);
goto err;
}
buf_expand_shell_variables(&value);
buf_expand_tilde(&value);
setenv(key, value.data, 1);
err:
buf_reset(&value);
}
#undef LAB_ENV_VAR_MAX_SIZE
/* return true on successful read */
static bool
read_environment_file(const char *filename)