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modpost: avoid false-positive file open error

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One problem of grab_file() is that it cannot distinguish the following
two cases:

 - It cannot read the file (the file does not exist, or read permission
   is not set)

 - It can read the file, but the file size is zero

This is because grab_file() calls mmap(), which requires the mapped
length is greater than 0. Hence, grab_file() fails for both cases.

If an empty header file were included for checksum calculation, the
following warning would be printed:

  WARNING: modpost: could not open ...: Invalid argument

An empty file is a valid source file, so it should not fail.

Use read_text_file() instead. It can read a zero-length file.
Then, parse_file() will succeed with doing nothing.

Going forward, the first case (it cannot read the file) is a fatal
error. If the source file from which an object was compiled is missing,
something went wrong.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This commit is contained in:
Masahiro Yamada 2020-06-01 14:57:19 +09:00
parent f531c1b5de
commit 7c8f5662c5
1 changed files with 3 additions and 4 deletions
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7
scripts/mod/sumversion.c
View file

@ -258,9 +258,8 @@ static int parse_file(const char *fname, struct md4_ctx *md)
char *file; char *file;
unsigned long i, len; unsigned long i, len;
file = grab_file(fname, &len); file = read_text_file(fname);
if (!file) len = strlen(file);
return 0;
for (i = 0; i < len; i++) { for (i = 0; i < len; i++) {
/* Collapse and ignore \ and CR. */ /* Collapse and ignore \ and CR. */
@ -287,7 +286,7 @@ static int parse_file(const char *fname, struct md4_ctx *md)
add_char(file[i], md); add_char(file[i], md);
} }
release_file(file, len); free(file);
return 1; return 1;
} }
/* Check whether the file is a static library or not */ /* Check whether the file is a static library or not */