[systemd-devel] [PATCH 7/8] add rpmvercmp()

[Shawn Landden]

---
 Makefile.am            |   2 +
 src/shared/rpmvercmp.c | 122 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/shared/rpmvercmp.h |  14 ++++++
 3 files changed, 138 insertions(+)
 create mode 100644 src/shared/rpmvercmp.c
 create mode 100644 src/shared/rpmvercmp.h

diff --git a/Makefile.am b/Makefile.am
index e0813a6..1310a20 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -900,6 +900,8 @@ libsystemd_shared_la_SOURCES = \
 	src/shared/nss-util.h \
 	src/shared/verbs.c \
 	src/shared/verbs.h \
+	src/shared/rpmvercmp.c \
+	src/shared/rpmvercmp.h \
 	src/shared/sigbus.c \
 	src/shared/sigbus.h \
 	src/shared/rbtree.c \
diff --git a/src/shared/rpmvercmp.c b/src/shared/rpmvercmp.c
new file mode 100644
index 0000000..c69c2e3
--- /dev/null
+++ b/src/shared/rpmvercmp.c
@@ -0,0 +1,122 @@
+/* From rpm (Library GPLv2+, which is compatible with LGPLv2.1+)
+ * git://rpm.org/rpm.git
+ */
+
+#include <stddef.h>
+#include <ctype.h>
+#include <string.h>
+
+#include "util.h"
+#include "rpmvercmp.h"
+
+/* compare alpha and numeric segments of two versions */
+/* return 1: a is newer than b */
+/*        0: a and b are the same version */
+/*       -1: b is newer than a */
+int rpmvercmp(const char * a, const char * b)
+{
+    /* easy comparison to see if versions are identical */
+    if (streq_ptr(a, b)) return 0;
+
+    char oldch1, oldch2;
+    char abuf[strlen(a)+1], bbuf[strlen(b)+1];
+    char *str1 = abuf, *str2 = bbuf;
+    char * one, * two;
+    int rc;
+    int isnum;
+
+    strcpy(str1, a);
+    strcpy(str2, b);
+
+    one = str1;
+    two = str2;
+
+    /* loop through each version segment of str1 and str2 and compare them */
+    while (*one || *two) {
+	while (*one && !isalnum(*one) && *one != '~') one++;
+	while (*two && !isalnum(*two) && *two != '~') two++;
+
+	/* handle the tilde separator, it sorts before everything else */
+	if (*one == '~' || *two == '~') {
+	    if (*one != '~') return 1;
+	    if (*two != '~') return -1;
+	    one++;
+	    two++;
+	    continue;
+	}
+
+	/* If we ran to the end of either, we are finished with the loop */
+	if (!(*one && *two)) break;
+
+	str1 = one;
+	str2 = two;
+
+	/* grab first completely alpha or completely numeric segment */
+	/* leave one and two pointing to the start of the alpha or numeric */
+	/* segment and walk str1 and str2 to end of segment */
+	if (isdigit(*str1)) {
+	    while (*str1 && isdigit(*str1)) str1++;
+	    while (*str2 && isdigit(*str2)) str2++;
+	    isnum = 1;
+	} else {
+	    while (*str1 && isalpha(*str1)) str1++;
+	    while (*str2 && isalpha(*str2)) str2++;
+	    isnum = 0;
+	}
+
+	/* save character at the end of the alpha or numeric segment */
+	/* so that they can be restored after the comparison */
+	oldch1 = *str1;
+	*str1 = '\0';
+	oldch2 = *str2;
+	*str2 = '\0';
+
+	/* this cannot happen, as we previously tested to make sure that */
+	/* the first string has a non-null segment */
+	if (one == str1) return -1;	/* arbitrary */
+
+	/* take care of the case where the two version segments are */
+	/* different types: one numeric, the other alpha (i.e. empty) */
+	/* numeric segments are always newer than alpha segments */
+	/* XXX See patch #60884 (and details) from bugzilla #50977. */
+	if (two == str2) return (isnum ? 1 : -1);
+
+	if (isnum) {
+	    size_t onelen, twolen;
+	    /* this used to be done by converting the digit segments */
+	    /* to ints using atoi() - it's changed because long  */
+	    /* digit segments can overflow an int - this should fix that. */
+
+	    /* throw away any leading zeros - it's a number, right? */
+	    while (*one == '0') one++;
+	    while (*two == '0') two++;
+
+	    /* whichever number has more digits wins */
+	    onelen = strlen(one);
+	    twolen = strlen(two);
+	    if (onelen > twolen) return 1;
+	    if (twolen > onelen) return -1;
+	}
+
+	/* strcmp will return which one is greater - even if the two */
+	/* segments are alpha or if they are numeric.  don't return  */
+	/* if they are equal because there might be more segments to */
+	/* compare */
+	rc = strcmp(one, two);
+	if (rc) return (rc < 1 ? -1 : 1);
+
+	/* restore character that was replaced by null above */
+	*str1 = oldch1;
+	one = str1;
+	*str2 = oldch2;
+	two = str2;
+    }
+
+    /* this catches the case where all numeric and alpha segments have */
+    /* compared identically but the segment sepparating characters were */
+    /* different */
+    if ((!*one) && (!*two)) return 0;
+
+    /* whichever version still has characters left over wins */
+    if (!*one) return -1; else return 1;
+}
diff --git a/src/shared/rpmvercmp.h b/src/shared/rpmvercmp.h
new file mode 100644
index 0000000..4ba6f36
--- /dev/null
+++ b/src/shared/rpmvercmp.h
@@ -0,0 +1,14 @@
+/* From rpm (Library GPLv2+, which is compatible with LGPLv2.1+)
+ * git://rpm.org/rpm.git
+ */
+
+#pragma once
+
+/** \ingroup rpmtrans
+ * Segmented string compare for version or release strings.
+ *
+ * @param a		1st string
+ * @param b		2nd string
+ * @return		+1 if a is "newer", 0 if equal, -1 if b is "newer"
+ */
+int rpmvercmp(const char * a, const char * b);
-- 
2.2.1.209.g41e5f3a