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Diffstat (limited to 'lib/strverscmp.c')
| -rw-r--r-- | lib/strverscmp.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/lib/strverscmp.c b/lib/strverscmp.c new file mode 100644 index 0000000000..da2d284918 --- /dev/null +++ b/lib/strverscmp.c @@ -0,0 +1,165 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Code taken from systemd src/fundamental/string-util-fundamental.c + * NOTE: Semantics differ from glibc strverscmp (e.g. handling of ~rc1) + */ + +#include <string.h> +#include <linux/ctype.h> +#include <linux/export.h> + +static bool is_valid_version_char(char a) +{ + return isdigit(a) || isalpha(a) || a == '~' || + a == '-' || a == '^' || a == '.'; +} + +int strverscmp(const char *a, const char *b) +{ + /* This function is similar to strverscmp(3), but it treats '-' and '.' as separators. + * + * The logic is based on rpm's rpmvercmp(), but unlike rpmvercmp(), it distiguishes e.g. + * '123a' and '123.a', with '123a' being newer. + * + * It allows direct comparison of strings which contain both a version and a release; e.g. + * '247.2-3.1.fc33.x86_64' or '5.11.0-0.rc5.20210128git76c057c84d28.137.fc34'. + * + * The input string is split into segments. Each segment is numeric or alphabetic, and may be + * prefixed with the following: + * '~' : used for pre-releases, a segment prefixed with this is the oldest, + * '-' : used for the separator between version and release, + * '^' : used for patched releases, a segment with this is newer than one with '-'. + * '.' : used for point releases. + * Note that no prefix segment is the newest. All non-supported characters are dropped, and + * handled as a separator of segments, e.g., '123_a' is equivalent to '123a'. + * + * By using this, version strings can be sorted like following: + * (older) 122.1 + * ^ 123~rc1-1 + * | 123 + * | 123-a + * | 123-a.1 + * | 123-1 + * | 123-1.1 + * | 123^post1 + * | 123.a-1 + * | 123.1-1 + * v 123a-1 + * (newer) 124-1 + */ + + a = a ?: ""; + b = b ?: ""; + + for (;;) { + const char *aa, *bb; + int r; + + /* Drop leading invalid characters. */ + while (*a != '\0' && !is_valid_version_char(*a)) + a++; + while (*b != '\0' && !is_valid_version_char(*b)) + b++; + + /* Handle '~'. Used for pre-releases, e.g. 123~rc1, or 4.5~alpha1 */ + if (*a == '~' || *b == '~') { + /* The string prefixed with '~' is older. */ + r = compare3(*a != '~', *b != '~'); + if (r != 0) + return r; + + /* Now both strings are prefixed with '~'. Compare remaining strings. */ + a++; + b++; + } + + /* If at least one string reaches the end, then longer is newer. + * Note that except for '~' prefixed segments, a string which has more segments is newer. + * So, this check must be after the '~' check. */ + if (*a == '\0' || *b == '\0') + return compare3(*a, *b); + + /* Handle '-', which separates version and release, e.g 123.4-3.1.fc33.x86_64 */ + if (*a == '-' || *b == '-') { + /* The string prefixed with '-' is older (e.g., 123-9 vs 123.1-1) */ + r = compare3(*a != '-', *b != '-'); + if (r != 0) + return r; + + a++; + b++; + } + + /* Handle '^'. Used for patched release. */ + if (*a == '^' || *b == '^') { + r = compare3(*a != '^', *b != '^'); + if (r != 0) + return r; + + a++; + b++; + } + + /* Handle '.'. Used for point releases. */ + if (*a == '.' || *b == '.') { + r = compare3(*a != '.', *b != '.'); + if (r != 0) + return r; + + a++; + b++; + } + + if (isdigit(*a) || isdigit(*b)) { + /* Find the leading numeric segments. One may be an empty string. So, + * numeric segments are always newer than alpha segments. */ + for (aa = a; isdigit(*aa); aa++) + ; + for (bb = b; isdigit(*bb); bb++) + ; + + /* Check if one of the strings was empty, but the other not. */ + r = compare3(a != aa, b != bb); + if (r != 0) + return r; + + /* Skip leading '0', to make 00123 equivalent to 123. */ + while (*a == '0') + a++; + while (*b == '0') + b++; + + /* To compare numeric segments without parsing their values, first compare the + * lengths of the segments. Eg. 12345 vs 123, longer is newer. */ + r = compare3(aa - a, bb - b); + if (r != 0) + return r; + + /* Then, compare them as strings. */ + r = compare3(strncmp(a, b, aa - a), 0); + if (r != 0) + return r; + } else { + /* Find the leading non-numeric segments. */ + for (aa = a; isalpha(*aa); aa++) + ; + for (bb = b; isalpha(*bb); bb++) + ; + + /* Note that the segments are usually not NUL-terminated. */ + r = compare3(strncmp(a, b, min(aa - a, bb - b)), 0); + if (r != 0) + return r; + + /* Longer is newer, e.g. abc vs abcde. */ + r = compare3(aa - a, bb - b); + if (r != 0) + return r; + } + + /* The current segments are equivalent. Let's move to the next one. */ + a = aa; + b = bb; + } +} +EXPORT_SYMBOL(strverscmp); |