initial raytracing experiment

[dosdemo] / src / dos / logger.c

diff --git a/src/dos/logger.c b/src/dos/logger.c
index 70489ad..2d61070 100644 (file)
--- a/src/dos/logger.c
+++ b/src/dos/logger.c
@@ -5,17 +5,63 @@
 #include <fcntl.h>
 #include "logger.h"
 
+static int logfd = -1, orig_fd1 = -1;
+
 int init_logger(const char *fname)
 {
-       int fd;
-       if((fd = open(fname, O_CREAT | O_WRONLY | O_TRUNC, 0644)) == -1) {
+       if(logfd != -1) return -1;
+
+       if((logfd = open(fname, O_CREAT | O_WRONLY | O_TRUNC, 0644)) == -1) {
                fprintf(stderr, "init_logger: failed to open %s: %s\n", fname, strerror(errno));
                return -1;
        }
 
+       orig_fd1 = dup(1);
        close(1);
        close(2);
-       dup(fd);
-       dup(fd);
+       dup(logfd);
+       dup(logfd);
+       return 0;
+}
+
+void stop_logger(void)
+{
+       if(logfd >= 0) {
+               close(logfd);
+               logfd = -1;
+       }
+       if(orig_fd1 >= 0) {
+               close(1);
+               close(2);
+               dup(orig_fd1);
+               dup(orig_fd1);
+               orig_fd1 = -1;
+       }
+}
+
+int print_tail(const char *fname)
+{
+       FILE *fp;
+       char buf[64];
+       long lineoffs[16];
+       int wr, rd, c;
+
+       if(!(fp = fopen(fname, "r"))) {
+               return -1;
+       }
+       lineoffs[wr++] = 0;
+       while(fgets(buf, sizeof buf, fp)) {
+               lineoffs[wr] = ftell(fp);
+               wr = (wr + 1) & 0xf;
+               if(wr == rd) {
+                       rd = (rd + 1) & 0xf;
+               }
+       }
+
+       fseek(fp, lineoffs[rd], SEEK_SET);
+       while((c = fgetc(fp)) != -1) {
+               fputc(c, stdout);
+       }
+       fclose(fp);
        return 0;
 }