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libmount: Preserve empty string value in optstr parsing 

Recent mount (since the switch to libmount in v2.22) drops the '=' in
mount options that are set to an empty value.  For example, the command
line below will be affected:

  # mount -o rw,myopt='' -t tmpfs tmpfs /mnt/tmp

Fix that by preserving an empty string in the options passed to the
mount(2) syscall when they are present on the command line.

Add test cases to ensure empty string handling is working as expected
and in order to prevent regressions in the future.

Also tested manually by stracing mount commands (on a kernel which
accepts a special extra option, for testing purposes.)

Before this commit:

  # strace -e mount ./mount -t tmpfs -o rw,myopt='' tmpfs /mnt/tmp
  mount("tmpfs", "/mnt/tmp", "tmpfs", MS_MGC_VAL, "myarg") = -1 EINVAL (Invalid argument)

After this commit:

  # strace -e mount ./mount -t tmpfs -o rw,myopt='' tmpfs /mnt/tmp
  mount("tmpfs", "/mnt/tmp", "tmpfs", MS_MGC_VAL, "myopt=") = 0

All test cases pass, including newly added test cases.  Also checked
them with valgrind using:

  $ tests/run.sh --memcheck libmount/optstr

Fixes #332.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
This commit is contained in:
Filipe Brandenburger 2016-08-10 13:27:07 -07:00
parent 7cd6d50aa9
commit 727c689908
9 changed files with 37 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
libmount/src/optstr.c
View File

@ -185,7 +185,7 @@ static int __mnt_optstr_append_option(char **optstr,
sz = osz + nsz + 1; /* 1: '\0' */
if (osz)
sz++; /* ',' options separator */
if (vsz)
if (value)
sz += vsz + 1; /* 1: '=' */
p = realloc(*optstr, sz);
@ -201,7 +201,7 @@ static int __mnt_optstr_append_option(char **optstr,
memcpy(p, name, nsz);
p += nsz;
if (vsz) {
if (value) {
*p++ = '=';
memcpy(p, value, vsz);
p += vsz;

1
tests/expected/libmount/optstr-append-empty-value Normal file
View File

@ -0,0 +1 @@
result: >aaa,bbb=BBB,ccc,ddd=<

1
tests/expected/libmount/optstr-deduplicate-empty Normal file
View File

@ -0,0 +1 @@
result: >bbb,ccc,xxx,ddd,AAA=,fff=eee<

1
tests/expected/libmount/optstr-prepend-empty-value Normal file
View File

@ -0,0 +1 @@
result: >ddd=,aaa,bbb=BBB,ccc<

1
tests/expected/libmount/optstr-remove-empty-value Normal file
View File

@ -0,0 +1 @@
result: >aaa,ccc<

1
tests/expected/libmount/optstr-set-empty Normal file
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@ -0,0 +1 @@
result: >aaa,bbb=,ccc<

1
tests/expected/libmount/optstr-set-new-empty Normal file
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@ -0,0 +1 @@
result: >aaa=,bbb=BBB,ccc<

1
tests/expected/libmount/optstr-set-new-end-empty Normal file
View File

@ -0,0 +1 @@
result: >aaa,bbb=BBB,ccc=<

28
tests/ts/libmount/optstr
View File

@ -20,6 +20,10 @@ ts_init_subtest "append-value"
ts_valgrind $TESTPROG --append "aaa,bbb=BBB,ccc" "ddd" "DDD" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "append-empty-value"
ts_valgrind $TESTPROG --append "aaa,bbb=BBB,ccc" "ddd" "" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "prepend"
ts_valgrind $TESTPROG --prepend "aaa,bbb=BBB,ccc" "ddd" &> $TS_OUTPUT
ts_finalize_subtest
@ -28,6 +32,10 @@ ts_init_subtest "prepend-value"
ts_valgrind $TESTPROG --prepend "aaa,bbb=BBB,ccc" "ddd" "DDD" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "prepend-empty-value"
ts_valgrind $TESTPROG --prepend "aaa,bbb=BBB,ccc" "ddd" "" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "set-remove"
ts_valgrind $TESTPROG --set "aaa,bbb=BBB,ccc" "bbb" &> $TS_OUTPUT
ts_finalize_subtest
@ -40,14 +48,26 @@ ts_init_subtest "set-large"
ts_valgrind $TESTPROG --set "aaa,bbb=BBB,ccc" "bbb" "XXX-YYY-ZZZ" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "set-empty"
ts_valgrind $TESTPROG --set "aaa,bbb=BBB,ccc" "bbb" "" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "set-new"
ts_valgrind $TESTPROG --set "aaa,bbb=BBB,ccc" "aaa" "XXX" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "set-new-empty"
ts_valgrind $TESTPROG --set "aaa,bbb=BBB,ccc" "aaa" "" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "set-new-end"
ts_valgrind $TESTPROG --set "aaa,bbb=BBB,ccc" "ccc" "XXX" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "set-new-end-empty"
ts_valgrind $TESTPROG --set "aaa,bbb=BBB,ccc" "ccc" "" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "get"
ts_valgrind $TESTPROG --get "aaa,bbb=BBB,ccc" "aaa" &> $TS_OUTPUT
ts_finalize_subtest
@ -68,6 +88,10 @@ ts_init_subtest "remove-value"
ts_valgrind $TESTPROG --remove "aaa,bbb=BBB,ccc" "bbb" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "remove-empty-value"
ts_valgrind $TESTPROG --remove "aaa,bbb=,ccc" "bbb" &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "split"
ts_valgrind $TESTPROG --split "aaa,bbb=BBB,ccc,x-bar,x-foo=foodata,user=kzak,noexec,nosuid,loop=/dev/loop0" &> $TS_OUTPUT
ts_finalize_subtest
@ -92,4 +116,8 @@ ts_init_subtest "deduplicate"
ts_valgrind $TESTPROG --dedup bbb,ccc,AAA,xxx,AAA=a,AAA=bbb,ddd,AAA=ccc,fff=eee AAA &> $TS_OUTPUT
ts_finalize_subtest
ts_init_subtest "deduplicate-empty"
ts_valgrind $TESTPROG --dedup bbb,ccc,AAA,xxx,AAA=a,AAA=bbb,ddd,AAA=,fff=eee AAA &> $TS_OUTPUT
ts_finalize_subtest
ts_finalize