diff mbox series

[PATCHv2,1/2] libiberty/buildargv: POSIX behaviour for backslash handling

Message ID e21f46e9ded3fecce996e3d1314fc30527d3ea39.1707585836.git.aburgess@redhat.com
State New
Headers show
Series Changes to libiberty buildargv | expand

Commit Message

Andrew Burgess Feb. 10, 2024, 5:26 p.m. UTC 
GDB makes use of the libiberty function buildargv for splitting the
inferior (program being debugged) argument string in the case where
the inferior is not being started under a shell.

I have recently been working to improve this area of GDB, and have
tracked done some of the unexpected behaviour to the libiberty
function buildargv, and how it handles backslash escapes.

For reference, I've been mostly reading:

  https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html

The issues that I would like to fix are:

  1. Backslashes within single quotes should not be treated as an
  escape, thus: '\a' should split to \a, retaining the backslash.

  2. Backslashes within double quotes should only act as an escape if
  they are immediately before one of the characters $ (dollar),
  ` (backtick), " (double quote), ` (backslash), or \n (newline).  In
  all other cases a backslash should not be treated as an escape
  character.  Thus: "\a" should split to \a, but "\$" should split to
  $.

  3. A backslash-newline sequence should be treated as a line
  continuation, both the backslash and the newline should be removed.

I've updated libiberty and also added some tests.  All the existing
libiberty tests continue to pass, but I'm not sure if there is more
testing that should be done, buildargv is used within lto-wraper.cc,
so maybe there's some testing folk can suggest that I run?
---
 libiberty/argv.c                      |  8 +++++--
 libiberty/testsuite/test-expandargv.c | 34 +++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/libiberty/argv.c b/libiberty/argv.c
index 45f16854603..d9d32e59e72 100644
--- a/libiberty/argv.c
+++ b/libiberty/argv.c
@@ -224,9 +224,13 @@  char **buildargv (const char *input)
 		  if (bsquote)
 		    {
 		      bsquote = 0;
-		      *arg++ = *input;
+		      if (*input != '\n')
+			*arg++ = *input;
 		    }
-		  else if (*input == '\\')
+		  else if (*input == '\\'
+			   && !squote
+			   && (!dquote
+			       || strchr ("$`\"\\\n", *(input + 1)) != NULL))
 		    {
 		      bsquote = 1;
 		    }
diff --git a/libiberty/testsuite/test-expandargv.c b/libiberty/testsuite/test-expandargv.c
index 1e9cb0a0d5a..ea1aeb0eda2 100644
--- a/libiberty/testsuite/test-expandargv.c
+++ b/libiberty/testsuite/test-expandargv.c
@@ -142,6 +142,40 @@  const char *test_data[] = {
   "b",
   0,
 
+  /* Test 7 - No backslash removal within single quotes.  */
+  "'a\\$VAR' '\\\"'",    /* Test 7 data */
+  ARGV0,
+  "@test-expandargv-7.lst",
+  0,
+  ARGV0,
+  "a\\$VAR",
+  "\\\"",
+  0,
+
+  /* Test 8 - Remove backslash / newline pairs.  */
+  "\"ab\\\ncd\" ef\\\ngh",    /* Test 8 data */
+  ARGV0,
+  "@test-expandargv-8.lst",
+  0,
+  ARGV0,
+  "abcd",
+  "efgh",
+  0,
+
+  /* Test 9 - Backslash within double quotes.  */
+  "\"\\$VAR\" \"\\`\" \"\\\"\" \"\\\\\" \"\\n\" \"\\t\"",    /* Test 9 data */
+  ARGV0,
+  "@test-expandargv-9.lst",
+  0,
+  ARGV0,
+  "$VAR",
+  "`",
+  "\"",
+  "\\",
+  "\\n",
+  "\\t",
+  0,
+
   0 /* Test done marker, don't remove. */
 };