initial commit

diff --git a/Makefile b/Makefile
new file mode 100644 (file)
index 0000000..660931f
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,13 @@
+
+PROG=  githead
+
+all: githead
+
+githead: githead.c
+       $(CC) -Os -pipe -o $@ $<
+
+#BINDIR=       /usr/local/bin
+#MANDIR=       /usr/local/man
+
+#.include <bsd.prog.mk>
+

diff --git a/githead.c b/githead.c
new file mode 100644 (file)
index 0000000..e258a5b
--- /dev/null
+++ b/githead.c
@@ -0,0 +1,166 @@
+
+/*
+ * Get the name of the current git branch (pointed to by HEAD) and print it
+ * out, color-coded to show if any working files are dirty.  This would
+ * ideally be implemented as a shell script, but I wrote it in C because it
+ * needs to be fast!  And we all know C is fast, amiright?
+ *
+ * Also reads in regular expressions (one per line) matching paths that
+ * should be ignored.  Each regex is matched against the top-level
+ * directory path of the repository.  If it matches, nothing is printed.
+ * It is a good idea to ignore repositories on slow (remote) disks.
+ *
+ * Example usage (bash):
+ * PS1='\u@\h \w$(githead <~/.nogitprompt) $ '
+ *
+ * Written 04 June 2012 by Charles McGarvey.
+ */
+
+const char* ansi_codes = "0;36";
+const char* ansi_codes_dirty = "0;31";
+
+#include <errno.h>
+#include <regex.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/wait.h>
+
+int main(int argc, char* argv[])
+{
+    char buf[4096];
+
+    char*   branch = NULL;
+    int     dirty = 0;
+
+    fclose(stderr);     // usually do not want any extra junk printed
+
+    int p[2];
+    if (pipe(p) == -1) {
+       fprintf(stderr, "pipe failed: %s\n", strerror(errno));
+       return 1;
+    }
+
+    pid_t pid1 = fork();
+    if (pid1 == -1) {
+       fprintf(stderr, "fork failed: %s\n", strerror(errno));
+       return 1;
+    }
+    if (pid1 == 0) {
+       char* args[] = {"git", "rev-parse", "--show-toplevel", NULL};
+       if (dup2(p[1], 1) == -1) {
+           fprintf(stderr, "dup2 failed: %s\n", strerror(errno));
+       }
+       execvp(args[0], args);
+       return 0;
+    }
+
+    close(p[1]);
+
+    int status;
+    while (waitpid(pid1, &status, 0) < 0) {
+       if (errno != EINTR) {
+           fprintf(stderr, "waitpid failed: %s\n", strerror(errno));
+           return 1;
+       }
+    }
+    if (WEXITSTATUS(status) == 0) {
+       ssize_t bytes = read(p[0], buf, sizeof(buf));
+       if (bytes < 0) {
+           fprintf(stderr, "read failed: %s\n", strerror(errno));
+           return 1;
+       }
+       buf[bytes-1] = '\0';
+
+       char regbuf[4096];
+       while (gets(regbuf)) {
+           char errbuf[4096];
+           regex_t re;
+           int err = regcomp(&re, regbuf, REG_EXTENDED | REG_ICASE | REG_NOSUB);
+           if (err != 0) {
+               regerror(err, &re, errbuf, sizeof(errbuf));
+               fprintf(stderr, "regcomp failed: %s\n", errbuf);
+               continue;
+           }
+           if (regexec(&re, buf, 0, NULL, 0) == 0) {
+               return 0;
+           }
+           regfree(&re);
+       }
+    }
+    else {
+       fprintf(stderr, "git failed; bailing out...\n");
+       return 1;
+    }
+
+    pid_t pid2 = fork();
+    if (pid2 == -1) {
+       fprintf(stderr, "fork failed: %s\n", strerror(errno));
+       return 1;
+    }
+    if (pid2 == 0) {
+       char* args[] = {"git", "diff", "--no-ext-diff", "--quiet", "--exit-code", NULL};
+       execvp(args[0], args);
+       return 0;
+    }
+
+    if (pipe(p) == -1) {
+       fprintf(stderr, "pipe failed: %s\n", strerror(errno));
+       return 1;
+    }
+
+    pid_t pid3 = fork();
+    if (pid3 == -1) {
+       fprintf(stderr, "fork failed: %s\n", strerror(errno));
+       return 1;
+    }
+    if (pid3 == 0) {
+       char* args[] = {"git", "symbolic-ref", "HEAD", NULL};
+       if (dup2(p[1], 1) == -1) {
+           fprintf(stderr, "dup2 failed: %s\n", strerror(errno));
+       }
+       execvp(args[0], args);
+       return 1;
+    }
+
+    close(p[1]);
+
+    while (waitpid(pid3, &status, 0) < 0) {
+       if (errno != EINTR) {
+           fprintf(stderr, "waitpid failed: %s\n", strerror(errno));
+           return 1;
+       }
+    }
+    if (WEXITSTATUS(status) == 0) {
+       ssize_t bytes = read(p[0], buf, sizeof(buf));
+       if (bytes < 0) {
+           fprintf(stderr, "read failed: %s\n", strerror(errno));
+           return 1;
+       }
+       buf[bytes-1] = '\0';
+       branch = buf + 11;
+    }
+
+    while (waitpid(pid2, &status, 0) < 0) {
+       if (errno != EINTR) {
+           fprintf(stderr, "waitpid failed: %s\n", strerror(errno));
+           return 1;
+       }
+    }
+    dirty = (WEXITSTATUS(status) != 0);
+
+    if (branch) {
+       if (dirty) {
+           printf("\033[%sm[%s]\033[0m", ansi_codes_dirty, branch);
+       }
+       else {
+           printf("\033[%sm[%s]\033[0m", ansi_codes, branch);
+       }
+    }
+
+    return 0;
+}
+