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string-util: let's add helper for truncating string after a specified number of lines

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This commit is contained in:
Lennart Poettering 2020-01-13 16:07:06 +01:00
parent 5749698031
commit 8dd6491ef9
3 changed files with 131 additions and 0 deletions
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57
src/basic/string-util.c
View File

@ -1074,3 +1074,60 @@ char* string_erase(char *x) {
explicit_bzero_safe(x, strlen(x));
return x;
}
int string_truncate_lines(const char *s, size_t n_lines, char **ret) {
const char *p = s, *e = s;
bool truncation_applied = false;
char *copy;
size_t n = 0;
assert(s);
/* Truncate after the specified number of lines. Returns > 0 if a truncation was applied or == 0 if
* there were fewer lines in the string anyway. Trailing newlines on input are ignored, and not
* generated either. */
for (;;) {
size_t k;
k = strcspn(p, "\n");
if (p[k] == 0) {
if (k == 0) /* final empty line */
break;
if (n >= n_lines) /* above threshold */
break;
e = p + k; /* last line to include */
break;
}
assert(p[k] == '\n');
if (n >= n_lines)
break;
if (k > 0)
e = p + k;
p += k + 1;
n++;
}
/* e points after the last character we want to keep */
if (isempty(e))
copy = strdup(s);
else {
if (!in_charset(e, "\n")) /* We only consider things truncated if we remove something that
* isn't a new-line or a series of them */
truncation_applied = true;
copy = strndup(s, e - s);
}
if (!copy)
return -ENOMEM;
*ret = copy;
return truncation_applied;
}

2
src/basic/string-util.h
View File

@ -280,3 +280,5 @@ static inline char* str_realloc(char **p) {
}
char* string_erase(char *x);
int string_truncate_lines(const char *s, size_t n_lines, char **ret);

72
src/test/test-string-util.c
View File

@ -563,6 +563,77 @@ static void test_memory_startswith_no_case(void) {
assert_se(memory_startswith_no_case((char[2]){'X', 'X'}, 2, "XX"));
}
static void test_string_truncate_lines_one(const char *input, size_t n_lines, const char *output, bool truncation) {
_cleanup_free_ char *b = NULL;
int k;
assert_se((k = string_truncate_lines(input, n_lines, &b)) >= 0);
assert_se(streq(b, output));
assert_se(!!k == truncation);
}
static void test_string_truncate_lines(void) {
test_string_truncate_lines_one("", 0, "", false);
test_string_truncate_lines_one("", 1, "", false);
test_string_truncate_lines_one("", 2, "", false);
test_string_truncate_lines_one("", 3, "", false);
test_string_truncate_lines_one("x", 0, "", true);
test_string_truncate_lines_one("x", 1, "x", false);
test_string_truncate_lines_one("x", 2, "x", false);
test_string_truncate_lines_one("x", 3, "x", false);
test_string_truncate_lines_one("x\n", 0, "", true);
test_string_truncate_lines_one("x\n", 1, "x", false);
test_string_truncate_lines_one("x\n", 2, "x", false);
test_string_truncate_lines_one("x\n", 3, "x", false);
test_string_truncate_lines_one("x\ny", 0, "", true);
test_string_truncate_lines_one("x\ny", 1, "x", true);
test_string_truncate_lines_one("x\ny", 2, "x\ny", false);
test_string_truncate_lines_one("x\ny", 3, "x\ny", false);
test_string_truncate_lines_one("x\ny\n", 0, "", true);
test_string_truncate_lines_one("x\ny\n", 1, "x", true);
test_string_truncate_lines_one("x\ny\n", 2, "x\ny", false);
test_string_truncate_lines_one("x\ny\n", 3, "x\ny", false);
test_string_truncate_lines_one("x\ny\nz", 0, "", true);
test_string_truncate_lines_one("x\ny\nz", 1, "x", true);
test_string_truncate_lines_one("x\ny\nz", 2, "x\ny", true);
test_string_truncate_lines_one("x\ny\nz", 3, "x\ny\nz", false);
test_string_truncate_lines_one("x\ny\nz\n", 0, "", true);
test_string_truncate_lines_one("x\ny\nz\n", 1, "x", true);
test_string_truncate_lines_one("x\ny\nz\n", 2, "x\ny", true);
test_string_truncate_lines_one("x\ny\nz\n", 3, "x\ny\nz", false);
test_string_truncate_lines_one("\n", 0, "", false);
test_string_truncate_lines_one("\n", 1, "", false);
test_string_truncate_lines_one("\n", 2, "", false);
test_string_truncate_lines_one("\n", 3, "", false);
test_string_truncate_lines_one("\n\n", 0, "", false);
test_string_truncate_lines_one("\n\n", 1, "", false);
test_string_truncate_lines_one("\n\n", 2, "", false);
test_string_truncate_lines_one("\n\n", 3, "", false);
test_string_truncate_lines_one("\n\n\n", 0, "", false);
test_string_truncate_lines_one("\n\n\n", 1, "", false);
test_string_truncate_lines_one("\n\n\n", 2, "", false);
test_string_truncate_lines_one("\n\n\n", 3, "", false);
test_string_truncate_lines_one("\nx\n\n", 0, "", true);
test_string_truncate_lines_one("\nx\n\n", 1, "", true);
test_string_truncate_lines_one("\nx\n\n", 2, "\nx", false);
test_string_truncate_lines_one("\nx\n\n", 3, "\nx", false);
test_string_truncate_lines_one("\n\nx\n", 0, "", true);
test_string_truncate_lines_one("\n\nx\n", 1, "", true);
test_string_truncate_lines_one("\n\nx\n", 2, "", true);
test_string_truncate_lines_one("\n\nx\n", 3, "\n\nx", false);
}
int main(int argc, char *argv[]) {
test_setup_logging(LOG_DEBUG);
@ -595,6 +666,7 @@ int main(int argc, char *argv[]) {
test_strlen_ptr();
test_memory_startswith();
test_memory_startswith_no_case();
test_string_truncate_lines();
return 0;
}