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[2/4] Split prefix-map values on the last '=' character, not the first

Message ID 20161102142356.5617-3-infinity0@pwned.gg
State New
Headers show

Commit Message

Ximin Luo Nov. 2, 2016, 2:23 p.m. UTC 
We are planning to ask other tools to support SOURCE_PREFIX_MAP, in the same
way that we have already done this for SOURCE_DATE_EPOCH. So, this will last
for some time and have quite wide reach. Consequently, we believe it is better
to split on the final '=', since it is much less likely to result in problems.

For example, with the previous behaviour (splitting on the first '=') it would
not be possible to map paths like the following:

C:\Documents and Settings\Betrand Russell\Proofs of 1+1=2\Automated Proofs\Source Code\
/srv/net/distributed-hash-table/address/VaIWP8YIWDChR2O76yiufXBsbw5g2skB_kp9VP-qVLvydovdGw==/projects/gcc-6/

These are contrived examples, but hopefully you can agree that they're not *so*
unrealistic - future software or users might plausibly wish to run reproducible
build processes underneath paths similar to these.

On the other hand, I can think of much fewer cases where the new-prefix *must*
include a '=' character. I can't think of any software project that includes
it, and I'd imagine that any such (or future) projects that might exist would
already have standardised "ASCII-only" versions of its name.

ChangeLogs
----------

gcc/ChangeLog:

2016-11-01  Ximin Luo  <infinity0@pwned.gg>

	* final.c: (add_debug_prefix_map): Split on the last and not first '='.
	* doc/invoke.texi (Environment Variables): Update SOURCE_PREFIX_MAP to
	describe new parsing.
diff mbox

Patch

Index: gcc-7-20161030/gcc/final.c
===================================================================
--- gcc-7-20161030.orig/gcc/final.c
+++ gcc-7-20161030/gcc/final.c
@@ -1528,7 +1528,7 @@  add_debug_prefix_map (const char *arg)
   debug_prefix_map *map;
   const char *p;
 
-  p = strchr (arg, '=');
+  p = strrchr (arg, '=');
   if (!p)
     {
       error ("invalid value %qs for debug-prefix-map", arg);
Index: gcc-7-20161030/gcc/doc/invoke.texi
===================================================================
--- gcc-7-20161030.orig/gcc/doc/invoke.texi
+++ gcc-7-20161030/gcc/doc/invoke.texi
@@ -26233,8 +26233,8 @@  output by higher-level build processes.
 
 The form and behaviour is similar to @option{-fdebug-prefix-map}. That
 is, the value of @env{SOURCE_PREFIX_MAP} must be of the form
-@samp{@var{old}=@var{new}}. The split occurs on the first @code{=}
-character, so that @var{old} cannot itself contain a @code{=}.
+@samp{@var{old}=@var{new}}. The split occurs on the last @code{=}
+character, so that @var{new} cannot itself contain a @code{=}.
 
 Whenever an absolute source- or build-related filepath is to be emitted
 in a final end-result output, GCC will replace @var{old} with @var{new}