nkiss

commit 7b179d04562e1e25ed0b1d093a99d9f21b8fcdb5
parent 5e7672736a68726a151262675c750b492e5d9fff
Author: Nihal Jere <nihal@nihaljere.xyz>
Date:   Mon, 22 Feb 2021 17:46:17 -0600

util.*: add file_dropadd

This function takes a path and two string parameters a and b, dropping
lines in the file point to by path that match a, and adding b, while
retaining lexographical sorting.

A function called 'mv' is also added, which moves a file, regardless of
what device its on.

Diffstat:
M
util.c
 | 
100
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
M
util.h
 | 
2
++

2 files changed, 99 insertions(+), 3 deletions(-)
diff --git a/util.c b/util.c
@@ -1,4 +1,6 @@
 /* See LICENSE file for copyright and license details. */
+#define _BSD_SOURCE
+
 #include <errno.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -7,10 +9,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <tls.h>
-
-#ifdef __OpenBSD__
 #include <unistd.h>
-#endif /* __OpenBSD__ */
 
 #include "util.h"
 
@@ -69,6 +68,101 @@ strrepl(char *str, const char a, const char b)
     }
 }
 
+int
+mv(char *oldpath, char *newpath)
+{
+    char buf[BUFSIZ];
+    FILE *old, *new;
+
+    /* try simply renaming */
+    if (rename(oldpath, newpath) == -1) {
+        /* if that doesn't work because its on a different device, we have to
+         * copy content of the file */
+        if (errno == EXDEV) {
+            if ((old = fopen(oldpath, "r")) == NULL)
+                return -1;
+
+            if ((new = fopen(newpath, "w")) == NULL) {
+                fclose(old);
+                return -1;
+            }
+
+            /* TODO proper error handling */
+            while (fgets(buf, BUFSIZ, old) != NULL)
+                fputs(buf, new);
+
+            fclose(old);
+            fclose(new);
+
+            unlink(oldpath);
+        } else return -1;
+    }
+
+    return 0;
+}
+
+/* drop lines matching a, add lines matching b, while retaining reverse
+ * lexographical sorting.
+ * the main use for this will be rewriting manifest files on alt swap */
+int
+file_dropadd(char *path, char *a, char *b)
+{
+    int fd, found = 0;
+    FILE *file, *temp;
+    char temppath[] = "/tmp/kissmanifestXXXXXX";
+    char line[512], *p;
+
+    if (!a || !b || !path)
+        return -1;
+
+    if ((fd = mkstemp(temppath)) == -1)
+        return -1;
+
+    if ((temp = fdopen(fd, "w")) == NULL) {
+        close(fd);
+        return -1;
+    }
+
+    if ((file = fopen(path, "r")) == NULL) {
+        fclose(temp);
+        return -1;
+    }
+
+    while (fgets(line, 512, file)) {
+        if ((p = strchr(line, '\n')) == NULL) {
+            fclose(temp);
+            fclose(file);
+            return -1;
+        }
+
+        /* temporarily replace newline with \0 so the comparison works */
+        *p = '\0';
+        if (strcmp(a, line) == 0)
+            continue;
+
+        /* insert b if greater than line.
+         * i think the edge case where strcmp(b, line) == 0 can be ignored, as
+         * a manifest shouldn't already contain b when dealing with
+         * alternatives */
+        if (!found && strcmp(b, line) > 0) {
+            found = 1;
+            fputs(b, temp);
+            fputc('\n', temp);
+        }
+
+        *p = '\n';
+        fputs(line, temp);
+    }
+
+    fclose(temp);
+    fclose(file);
+
+    if (mv(temppath, path) == -1)
+        return -1;
+
+    return 0;
+}
+
 /* essentially mkdir -p */
 int
 mkdirs(const char *path)
diff --git a/util.h b/util.h
@@ -16,5 +16,7 @@ void die(const char *, ...);
 int vstrcmp(const void *p1, const void *p2);
 void strrepl(char *str, const char a, const char b);
 int mkdirs(const char *path);
+int mv(char *oldpath, char *newpath);
+int file_dropadd(char *path, char *a, char *b);
 
 #endif /* UTIL_H */