[PATCH 2/2] gdb: Resolve local source-highlight data directory

[Stephanos Ioannidis <root@stephanos.io>]

The source-highlight data directory, which contains the input language
and output format definition files, is currently resolved by the
source-highlight library as one of the following:

 * Path specified by the environment variable SOURCE_HIGHLIGHT_DATADIR
 * Path specified by the source-highlight configuration file under HOME
 * Internally hard-coded path based on the installation prefix

This is less than ideal because users need to install a copy of the
source-highlight program on their system, and either manually set the
SOURCE_HIGHLIGHT_DATADIR environment variable to the path of the
directory containing the source-highlight data files or provide a
source-highlight configuration file under HOME that specifies the data
directory path.

This patch adds the logic to resolve, when exists, the path of the
source-highlight data directory embedded in the gdb data directory,
such that the source code syntax highlighting feature can function
independent of the host system dependencies and configurations.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
---
 gdb/source-cache.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/gdb/source-cache.c b/gdb/source-cache.c
index 0561a26737..aa1b5b3dc7 100644
--- a/gdb/source-cache.c
+++ b/gdb/source-cache.c
@@ -35,6 +35,7 @@
 #undef close
 #include <sstream>
 #include <srchilite/sourcehighlight.h>
+#include <srchilite/settings.h>
 #include <srchilite/langmap.h>
 #endif
 
@@ -194,6 +195,21 @@ source_cache::ensure (struct symtab *s)
 	    {
 	      if (highlighter == nullptr)
 		{
+		  /* Configure source-highlight data directory path to the GDB
+		   * local data directory path unless it is missing */
+		  std::string datadir = gdb_datadir + "/source-highlight";
+
+		  struct stat st;
+		  static srchilite::Settings settings;
+
+		  if (stat (datadir.c_str (), &st) == 0
+		      && S_ISDIR (st.st_mode))
+		    {
+		      settings.setGlobalDataDir(datadir);
+		    }
+
+		  /* Create a highlighter instance that outputs the ANSI
+		   * escape code-based color output */
 		  highlighter = new srchilite::SourceHighlight ("esc.outlang");
 		  highlighter->setStyleFile ("esc.style");
 		}
-- 
2.26.2