[Mesa-dev] [PATCH v2 2/2] mesa: load a user defined drirc file specified via an environment variable

[Edmondo Tommasina]

Introduce a new MESA_USER_DRIRC environment variable to load a customized
drirc file.

This can be used mostly for two things:
1. Force the load of a different user drirc configuration for an application
   without touching/creating a user global ${HOME}/.drirc file or passing
   their values through a list of env variables.
2. Avoid the load of the ${HOME}/.drirc file and ensure that only the
   system /etc/drirc file is used.

Examples:
1. Set the variable to a file to load it instead of ${HOME}/.drirc:
   MESA_USER_DRIRC=~/glthread.drirc glxgears

2. Set the variable to an empty string to avoid the load of the user
   defined ${HOME}/.drirc file (if it exists):
   MESA_USER_DRIRC="" glxgears

v2:
  - extend the documentation of the envvar usage (Gustaw)
  - describe usefulness of the envvar in commit message (Eric)
---
 docs/envvars.html                       |  7 +++++++
 src/mesa/drivers/dri/common/xmlconfig.c | 26 +++++++++++++++++---------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/docs/envvars.html b/docs/envvars.html
index 653736565e..44a5ef6c74 100644
--- a/docs/envvars.html
+++ b/docs/envvars.html
@@ -130,6 +130,13 @@ that variable is set), or else within .cache/mesa within the user's
 home directory.
 <li>MESA_GLSL - <a href="shading.html#envvars">shading language compiler options</a>
 <li>MESA_NO_MINMAX_CACHE - when set, the minmax index cache is globally disabled.
+<li>MESA_USER_DRIRC - load a user defined drirc file, instead of the default
+.drirc file in the user home directory. Setting the variable to an empty
+string will also avoid to load the default user .drirc file. Examples:
+<ul>
+   <li>MESA_USER_DRIRC="/tmp/special.drirc" loads a special config file
+   <li>MESA_USER_DRIRC="" skips the load of the default ${HOME}/.drirc
+</ul>
 </ul>
 
 
diff --git a/src/mesa/drivers/dri/common/xmlconfig.c b/src/mesa/drivers/dri/common/xmlconfig.c
index fef007996e..dd4b46f3a4 100644
--- a/src/mesa/drivers/dri/common/xmlconfig.c
+++ b/src/mesa/drivers/dri/common/xmlconfig.c
@@ -988,7 +988,6 @@ driParseConfigFiles(driOptionCache *cache, const driOptionCache *info,
                     int screenNum, const char *driverName)
 {
     char *filenames[2] = { SYSCONFDIR "/drirc", NULL};
-    char *home;
     uint32_t i;
     struct OptConfData userData;
 
@@ -999,14 +998,23 @@ driParseConfigFiles(driOptionCache *cache, const driOptionCache *info,
     userData.driverName = driverName;
     userData.execName = GET_PROGRAM_NAME();
 
-    if ((home = getenv ("HOME"))) {
-        uint32_t len = strlen (home);
-        filenames[1] = malloc(len + 7+1);
-        if (filenames[1] == NULL)
-            __driUtilMessage ("Can't allocate memory for %s/.drirc.", home);
-        else {
-            memcpy (filenames[1], home, len);
-            memcpy (filenames[1] + len, "/.drirc", 7+1);
+    const char *userDrirc = getenv("MESA_USER_DRIRC");
+
+    if (userDrirc) {
+        filenames[1] = malloc(strlen(userDrirc) + 1);
+        strcpy(filenames[1], userDrirc);
+    }
+    else {
+        const char *home = getenv("HOME");
+        if (home) {
+            uint32_t len = strlen (home);
+            filenames[1] = malloc(len + 7+1);
+            if (filenames[1] == NULL)
+                __driUtilMessage ("Can't allocate memory for %s/.drirc.", home);
+            else {
+                memcpy (filenames[1], home, len);
+                memcpy (filenames[1] + len, "/.drirc", 7+1);
+            }
         }
     }
 
-- 
2.11.0