From 5e1d530da87a6d2aa7e719744cb278e7e54a6623 Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Sat, 10 Feb 2024 11:22:13 +0000 Subject: [PATCH] libiberty/buildargv: handle input consisting of only white space 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 noticed some unexpected behaviour to the libiberty function buildargv, when the input is a string consisting only of white space. What I observe is that if the input to buildargv is a string containing only white space, then buildargv will return an argv list containing a single empty argument, e.g.: char **argv = buildargv (" "); assert (*argv[0] == '\0'); assert (argv[1] == NULL); We get the same output from buildargv if the input is a single space, or multiple spaces. Other white space characters give the same results. This doesn't seem right to me, and in fact, there appears to be a work around for this issue in expandargv where we have this code: /* If the file is empty or contains only whitespace, buildargv would return a single empty argument. In this context we want no arguments, instead. */ if (only_whitespace (buffer)) { file_argv = (char **) xmalloc (sizeof (char *)); file_argv[0] = NULL; } else /* Parse the string. */ file_argv = buildargv (buffer); I think that the correct behaviour in this situation is to return an empty argv array, e.g.: char **argv = buildargv (" "); assert (argv[0] == NULL); And it turns out that this is a trivial change to buildargv. The diff does look big, but this is because I've re-indented a block. Check with 'git diff -b' to see the minimal changes. I've also removed the work around from expandargv. When testing this sort of thing I normally write the tests first, and then fix the code. In this case test-expandargv.c has sort-of been used as a mechanism for testing the buildargv function (expandargv does call buildargv most of the time), however, for this particular issue the work around in expandargv (mentioned above) masked the buildargv bug. I did consider adding a new test-buildargv.c file, however, this would have basically been a copy & paste of test-expandargv.c (with some minor changes to call buildargv). This would be fine now, but feels like we would eventually end up with one file not being updated as much as the other, and so test coverage would suffer. Instead, I have added some explicit buildargv testing to the test-expandargv.c file, this reuses the test input that is already defined for expandargv. Of course, once I removed the work around from expandargv then we now do always call buildargv from expandargv, and so the bug I'm fixing would impact both expandargv and buildargv, so maybe the new testing is redundant? I tend to think more testing is always better, so I've left it in for now. 2024-07-16 Andrew Burgess libiberty/ * argv.c (buildargv): Treat input of only whitespace as an empty argument list. (expandargv): Remove work around for intput that is only whitespace. * testsuite/test-expandargv.c: Add new tests 10, 11, and 12. Extend testing to call buildargv in more cases. --- libiberty/argv.c | 114 ++++++++++----------- libiberty/testsuite/test-expandargv.c | 136 ++++++++++++++++++++++---- 2 files changed, 169 insertions(+), 81 deletions(-) diff --git a/libiberty/argv.c b/libiberty/argv.c index d9d32e59e72..675336273f3 100644 --- a/libiberty/argv.c +++ b/libiberty/argv.c @@ -212,71 +212,74 @@ char **buildargv (const char *input) argv[argc] = NULL; } /* Begin scanning arg */ - arg = copybuf; - while (*input != EOS) + if (*input != EOS) { - if (ISSPACE (*input) && !squote && !dquote && !bsquote) + arg = copybuf; + while (*input != EOS) { - break; - } - else - { - if (bsquote) + if (ISSPACE (*input) && !squote && !dquote && !bsquote) { - bsquote = 0; - if (*input != '\n') - *arg++ = *input; - } - else if (*input == '\\' - && !squote - && (!dquote - || strchr ("$`\"\\\n", *(input + 1)) != NULL)) - { - bsquote = 1; - } - else if (squote) - { - if (*input == '\'') - { - squote = 0; - } - else - { - *arg++ = *input; - } - } - else if (dquote) - { - if (*input == '"') - { - dquote = 0; - } - else - { - *arg++ = *input; - } + break; } else { - if (*input == '\'') + if (bsquote) { - squote = 1; + bsquote = 0; + if (*input != '\n') + *arg++ = *input; } - else if (*input == '"') + else if (*input == '\\' + && !squote + && (!dquote + || strchr ("$`\"\\\n", *(input + 1)) != NULL)) { - dquote = 1; + bsquote = 1; + } + else if (squote) + { + if (*input == '\'') + { + squote = 0; + } + else + { + *arg++ = *input; + } + } + else if (dquote) + { + if (*input == '"') + { + dquote = 0; + } + else + { + *arg++ = *input; + } } else { - *arg++ = *input; + if (*input == '\'') + { + squote = 1; + } + else if (*input == '"') + { + dquote = 1; + } + else + { + *arg++ = *input; + } } + input++; } - input++; } + *arg = EOS; + argv[argc] = xstrdup (copybuf); + argc++; } - *arg = EOS; - argv[argc] = xstrdup (copybuf); - argc++; argv[argc] = NULL; consume_whitespace (&input); @@ -439,17 +442,8 @@ expandargv (int *argcp, char ***argvp) } /* Add a NUL terminator. */ buffer[len] = '\0'; - /* If the file is empty or contains only whitespace, buildargv would - return a single empty argument. In this context we want no arguments, - instead. */ - if (only_whitespace (buffer)) - { - file_argv = (char **) xmalloc (sizeof (char *)); - file_argv[0] = NULL; - } - else - /* Parse the string. */ - file_argv = buildargv (buffer); + /* Parse the string. */ + file_argv = buildargv (buffer); /* If *ARGVP is not already dynamically allocated, copy it. */ if (*argvp == original_argv) *argvp = dupargv (*argvp); diff --git a/libiberty/testsuite/test-expandargv.c b/libiberty/testsuite/test-expandargv.c index ea1aeb0eda2..ca7031eaf68 100644 --- a/libiberty/testsuite/test-expandargv.c +++ b/libiberty/testsuite/test-expandargv.c @@ -176,6 +176,30 @@ const char *test_data[] = { "\\t", 0, + /* Test 10 - Mixed white space characters. */ + "\t \n \t ", /* Test 10 data */ + ARGV0, + "@test-expandargv-10.lst", + 0, + ARGV0, + 0, + + /* Test 11 - Single ' ' character. */ + " ", /* Test 11 data */ + ARGV0, + "@test-expandargv-11.lst", + 0, + ARGV0, + 0, + + /* Test 12 - Multiple ' ' characters. */ + " ", /* Test 12 data */ + ARGV0, + "@test-expandargv-12.lst", + 0, + ARGV0, + 0, + 0 /* Test done marker, don't remove. */ }; @@ -265,6 +289,78 @@ erase_test (int test) fatal_error (__LINE__, "Failed to erase test file.", errno); } +/* compare_argv: + TEST is the current test number, and NAME is a short string to identify + which libibery function is being tested. ARGC_A and ARGV_A describe an + argument array, and this is compared to ARGC_B and ARGV_B, return 0 if + the two arrays match, otherwise return 1. */ + +static int +compare_argv (int test, const char *name, int argc_a, char *argv_a[], + int argc_b, char *argv_b[]) +{ + int failed = 0, k; + + if (argc_a != argc_b) + { + printf ("FAIL: test-%s-%d. Argument count didn't match\n", name, test); + failed = 1; + } + /* Compare each of the argv's ... */ + else + for (k = 0; k < argc_a; k++) + if (strcmp (argv_a[k], argv_b[k]) != 0) + { + printf ("FAIL: test-%s-%d. Arguments don't match.\n", name, test); + failed = 1; + break; + } + + if (!failed) + printf ("PASS: test-%s-%d.\n", name, test); + + return failed; +} + +/* test_buildargv + Test the buildargv function from libiberty. TEST is the current test + number and TEST_INPUT is the string to pass to buildargv (after calling + run_replaces on it). ARGC_AFTER and ARGV_AFTER are the expected + results. Return 0 if the test passes, otherwise return 1. */ + +static int +test_buildargv (int test, const char * test_input, int argc_after, + char *argv_after[]) +{ + char * input, ** argv; + size_t len; + int argc, failed; + + /* Generate RW copy of data for replaces */ + len = strlen (test_input); + input = malloc (sizeof (char) * (len + 1)); + if (input == NULL) + fatal_error (__LINE__, "Failed to malloc buildargv input buffer.", errno); + + memcpy (input, test_input, sizeof (char) * (len + 1)); + /* Run all possible replaces */ + run_replaces (input); + + /* Split INPUT into separate arguments. */ + argv = buildargv (input); + + /* Count the arguments we got back. */ + argc = 0; + while (argv[argc]) + ++argc; + + failed = compare_argv (test, "buildargv", argc_after, argv_after, argc, argv); + + free (input); + freeargv (argv); + + return failed; +} /* run_tests: Run expandargv @@ -276,12 +372,16 @@ run_tests (const char **test_data) { int argc_after, argc_before; char ** argv_before, ** argv_after; - int i, j, k, fails, failed; + int i, j, k, fails; + const char * input_str; i = j = fails = 0; /* Loop over all the tests */ while (test_data[j]) { + /* Save original input in case we run a buildargv test. */ + input_str = test_data[j]; + /* Write test data */ writeout_test (i, test_data[j++]); /* Copy argv before */ @@ -305,29 +405,23 @@ run_tests (const char **test_data) for (k = 0; k < argc_after; k++) run_replaces (argv_after[k]); + /* If the test input is just a file to expand then we can also test + calling buildargv directly as the expected output is equivalent to + calling buildargv on the contents of the file. + + The results of calling buildargv will not include the ARGV0 constant, + which is why we pass 'argc_after - 1' and 'argv_after + 1', this skips + over the ARGV0 in the expected results. */ + if (argc_before == 2) + fails += test_buildargv (i, input_str, argc_after - 1, argv_after + 1); + else + printf ("SKIP: test-buildargv-%d. This test isn't for buildargv\n", i); + /* Run test: Expand arguments */ expandargv (&argc_before, &argv_before); - failed = 0; - /* Compare size first */ - if (argc_before != argc_after) - { - printf ("FAIL: test-expandargv-%d. Number of arguments don't match.\n", i); - failed++; - } - /* Compare each of the argv's ... */ - else - for (k = 0; k < argc_after; k++) - if (strcmp (argv_before[k], argv_after[k]) != 0) - { - printf ("FAIL: test-expandargv-%d. Arguments don't match.\n", i); - failed++; - } - - if (!failed) - printf ("PASS: test-expandargv-%d.\n", i); - else - fails++; + fails += compare_argv (i, "expandargv", argc_before, argv_before, + argc_after, argv_after); freeargv (argv_before); freeargv (argv_after);