[PATCH 0/2] Fix gcc 8.1 warnings

[PATCH 0/2] Fix gcc 8.1 warnings

[Tomohiro Kusumi]

Fix gcc 8.1 warnings on strncpy()'s length argument.

Tomohiro Kusumi (2):
  exp: Fix -Wstringop-overflow= warning on gcc 8.1
  init: Fix -Wstringop-truncation warning on gcc 8.1

 exp/expression-parser.y |    2 +-
 init.c                  |    3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

[PATCH 1/2] exp: Fix -Wstringop-overflow= warning on gcc 8.1

[Tomohiro Kusumi]

gcc 8.1 on DragonFlyBSD is warning below.

It seems to be saying max copy length shouldn't depend on
the input string itself, so change the length argument to
"sizeof(lexer_input_buffer)-3" without strlen() involved,
followed by explicit \0 termination at the end of source
string length or at "sizeof(lexer_input_buffer)-3".

(-3 comes from what this function has been using.)

--
    CC y.tab.o
In function 'setup_to_parse_string',
    inlined from 'evaluate_arithmetic_expression' at y.tab.c:317:2:
y.tab.c:305:2: warning: 'strncpy' specified bound depends on the length of the source argument [-Wstringop-overflow=]
  strncpy(lexer_input_buffer, string, len);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
y.tab.c: In function 'evaluate_arithmetic_expression':
y.tab.c:301:8: note: length computed here
  len = strlen(string);
        ^~~~~~~~~~~~~~

Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
---
 exp/expression-parser.y |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/exp/expression-parser.y b/exp/expression-parser.y
index 04a6e07..29e2bcf 100644
--- a/exp/expression-parser.y
+++ b/exp/expression-parser.y
@@ -208,7 +208,7 @@ static void setup_to_parse_string(const char *string)
 	if (len > sizeof(lexer_input_buffer) - 3)
 		len = sizeof(lexer_input_buffer) - 3;
 
-	strncpy(lexer_input_buffer, string, len);
+	strncpy(lexer_input_buffer, string, sizeof(lexer_input_buffer)-3);
 	lexer_input_buffer[len] = '\0'; 
 	lexer_input_buffer[len + 1] = '\0';  /* lex/yacc want string double null terminated! */
 	lexer_read_offset = 0;
-- 
1.7.1

[PATCH 2/2] init: Fix -Wstringop-truncation warning on gcc 8.1

[Tomohiro Kusumi]

gcc 8.1 on DragonFlyBSD is warning below.

The code looks correct, but gcc 8.1 seems to be complaining
on length argument "strlen(filename)".

Replacing the length with "len - ((ts - file) + 1) - 1",
(i.e. buffer_size - leading_directory_size_with_slash - 1)
can silence the warning, but this equals "strlen(filename)".
Neither allows copying beyond limit of "full_fn" whose size
is "len".

--
init.c:2042:6: warning: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Wstringop-truncation]
      strncpy(full_fn + (ts - file) + 1,
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       filename, strlen(filename));
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
---
 init.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/init.c b/init.c
index a2b70c4..682a0c2 100644
--- a/init.c
+++ b/init.c
@@ -2040,7 +2040,8 @@ static int __parse_jobs_ini(struct thread_data *td,
 					strncpy(full_fn,
 						file, (ts - file) + 1);
 					strncpy(full_fn + (ts - file) + 1,
-						filename, strlen(filename));
+						filename,
+						len - ((ts - file) + 1) - 1);
 					full_fn[len - 1] = 0;
 					filename = full_fn;
 				}
-- 
1.7.1