Initial commit

1 files changed, 190 insertions, 0 deletions

diff --git a/src/mysqlerl.c b/src/mysqlerl.c
new file mode 100644
index 0000000..d65dba1
--- /dev/null
+++ b/src/mysqlerl.c
@@ -0,0 +1,190 @@
+#include <mysql.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+const char *LOGPATH = "/tmp/mysqlerl.log";
+const size_t BUFSIZE = 2048;
+static FILE *logfile = NULL;
+
+typedef u_int32_t msglen_t;
+
+void
+openlog()
+{
+  logfile = fopen(LOGPATH, "a");
+}
+
+void
+closelog()
+{
+  fclose(logfile);
+}
+
+void
+logmsg(const char *format, ...)
+{
+  FILE *out = logfile;
+  va_list args;
+
+  if (logfile == NULL)
+    logfile = stderr;
+
+  va_start(args, format);
+  (void)vfprintf(logfile, format, args);
+  (void)fprintf(logfile, "\n");
+  va_end(args);
+
+  fflush(logfile);
+}
+
+int
+restartable_read(char *buf, size_t buflen)
+{
+  ssize_t rc, readb;
+
+  rc = 0;
+  READLOOP:
+  while (rc < buflen) {
+    readb = read(STDIN_FILENO, buf + rc, buflen - rc);
+    if (readb == -1) {
+      if (errno == EAGAIN || errno == EINTR)
+        goto READLOOP;
+
+      return -1;
+    } else if (readb == 0) {
+      logmsg("ERROR: EOF trying to read additional %d bytes from "
+             "standard input", buflen - rc);
+      return -1;
+    }
+
+    rc += readb;
+  }
+
+  return rc;
+}
+
+int
+restartable_write(const char *buf, size_t buflen)
+{
+  ssize_t rc, wroteb;
+
+  rc = 0;
+  WRITELOOP:
+  while (rc < buflen) {
+    wroteb = write(STDOUT_FILENO, buf + rc, buflen - rc);
+    if (wroteb == -1) {
+      if (errno == EAGAIN || errno == EINTR)
+        goto WRITELOOP;
+
+      return -1;
+    }
+
+    rc += wroteb;
+  }
+
+  return rc;
+}
+
+char *
+read_cmd()
+{
+  char *buf;
+  msglen_t len;
+
+  logmsg("DEBUG: reading message length.");
+  if (restartable_read((char *)&len, sizeof(len)) == -1) {
+    logmsg("ERROR: couldn't read %d byte message prefix: %s.",
+           sizeof(len), strerror(errno));
+    exit(2);
+  }
+  len = ntohl(len);
+
+  buf = malloc(len);
+  if (buf == NULL) {
+    logmsg("ERROR: Couldn't malloc %d bytes: %s.", len,
+           strerror(errno));
+    exit(2);
+  }
+  memset(buf, 0, BUFSIZE);
+
+  logmsg("DEBUG: reading message body (len: %d).", len);
+  if (restartable_read(buf, len) == -1) {
+    logmsg("ERROR: couldn't read %d byte message: %s.",
+           len, strerror(errno));
+    exit(2);
+  }
+
+  return buf;
+}
+
+int
+write_cmd(const char *cmd, msglen_t len)
+{
+  msglen_t nlen;
+
+  nlen = htonl(len + 3);
+  restartable_write((char *)&nlen, sizeof(nlen));
+  restartable_write(" - ", 3);
+  restartable_write(cmd, len);
+}
+
+void
+dispatch_db_cmd(MYSQL *dbh, const char *cmd)
+{
+  msglen_t len, nlen;
+
+  logmsg("DEBUG: dispatch_cmd(\"%s\")", cmd);
+  write_cmd(cmd, strlen(cmd));
+}
+
+void
+usage()
+{
+  fprintf(stderr, "Usage: mysqlerl host port db_name user passwd\n");
+  exit(1);
+}
+
+int
+main(int argc, char *argv[])
+{
+  MYSQL dbh;
+  char *host, *port, *db_name, *user, *passwd, *cmd;
+
+  openlog();
+  logmsg("INFO: starting up.");
+
+  if (argc < 6)
+    usage();
+
+  host    = argv[1];
+  port    = argv[2];
+  db_name = argv[3];
+  user    = argv[4];
+  passwd  = argv[5];
+
+  mysql_init(&dbh);
+  if (mysql_real_connect(&dbh, host, user, passwd,
+                         db_name, atoi(port), NULL, 0) == NULL) {
+    logmsg("ERROR: Failed to connect to database %s: %s (%s:%s).",
+           db_name, mysql_error(&dbh), user, passwd);
+    exit(2);
+  }
+
+  while ((cmd = read_cmd()) != NULL) {
+    dispatch_db_cmd(&dbh, cmd);
+    free(cmd);
+  }
+
+  mysql_close(&dbh);
+
+  logmsg("INFO: shutting down.");
+  closelog();
+
+  return 0;
+}