Add catcho WIP

1 files changed, 204 insertions, 0 deletions

diff --git a/catcho.c b/catcho.c
new file mode 100644
index 0000000..3426e50
--- /dev/null
+++ b/catcho.c
@@ -0,0 +1,204 @@
+/*
+ * catcho - outputing text to the standard output
+ *
+ * Usage
+ * -----
+ *  catcho [options]
+ *
+ * Options
+ * -------
+ *  -m --mode MODE      Set the initial text mode (Default: passthrough)
+ *  -v --version        Display program information and exit
+ *  -V --verbose        Duplicate stdout on stderr
+ *
+ * Modes
+ * -----
+ *  passthru / passthrough / normal / n - Input is copied to output verbatim.
+ *  null / z - Input is dropped.
+ *  hb - Input (interpreted as hex) is compressed to bytes on the output.
+ *  bh - The opposite of hb.
+ *  ib - Input (interpreted as bit-bytes) is compressed to bytes on the output.
+ *  bi - The opposite of ib.
+ *
+ *  Append 'f' to any mode (eg:  bhf):  Input is interpreted as '\n'-delimited
+ *  filenames.  File contents are filtered based on mode and sent to output.
+ *
+ * Switching modes
+ * ---------------
+ *  When catcho receives signal SIGINT (ctrl-C from the terminal, for example),
+ *  any pending input/output is flushed and catcho then interprets the input
+ *  as a mode name terminated by a '\n'.  Once the input provides a string\n,
+ *  it switches the desired mode and input processing resumes.
+ *
+ * Exiting catcho
+ * --------------
+ *  Since SIGINT is used for mode switching, the 'normal' way to terminate
+ *  catcho is by sending it an End-Of-File byte on its input. (ctrl-D on your
+ *  terminal)
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <signal.h>
+
+#define LAST_STR_CHAR(s) (s[strlen(s)-1])
+
+/* modes */
+enum mode
+{
+    N,
+    Z,
+    HB,
+    BH,
+    IB,
+    BI
+};
+
+/* global state */
+static enum mode current_mode = N;
+static int  current_mode_f = 0;
+static int  current_verbose = 0;
+
+static size_t ccfwrite(const void *ptr, size_t size, size_t nmemb)
+{
+    size_t ret;
+    ret = fwrite(ptr, size, nmemb, stdout);
+
+    if (current_verbose)
+        fwrite(ptr, size, nmemb, stderr);
+
+    return ret;
+}
+
+static void sigint(int sig)
+{
+    (void)sig;
+    ccfwrite("in signal handler\n", 18, 1);
+}
+
+static int set_mode(const char *mode)
+{
+    if (!mode)
+        return 0;
+
+    if (!strcmp(mode, "passthru") || // these don't support 'f' suffix
+        !strcmp(mode, "passthrough") ||
+        !strcmp(mode, "normal"))
+    {
+        current_mode = N;
+        current_mode_f = 0;
+    }
+    else if (!strcmp(mode, "null")) // this doesn't support 'f' suffix
+    {
+        current_mode = Z;
+        current_mode_f = 0;
+    }
+    else if (!strncmp(mode, "n", 1))
+    {
+        current_mode = N;
+        current_mode_f = (LAST_STR_CHAR(mode) == 'f');
+    }
+    else if (!strncmp(mode, "z", 1))
+    {
+        current_mode = Z;
+        current_mode_f = (LAST_STR_CHAR(mode) == 'f');
+    }
+    else if (!strncmp(mode, "hb", 2))
+    {
+        current_mode = HB;
+        current_mode_f = (LAST_STR_CHAR(mode) == 'f');
+    }
+    else if (!strncmp(mode, "bh", 2))
+    {
+        current_mode = BH;
+        current_mode_f = (LAST_STR_CHAR(mode) == 'f');
+    }
+    else if (!strncmp(mode, "ib", 2))
+    {
+        current_mode = IB;
+        current_mode_f = (LAST_STR_CHAR(mode) == 'f');
+    }
+    else if (!strncmp(mode, "bi", 2))
+    {
+        current_mode = BI;
+        current_mode_f = (LAST_STR_CHAR(mode) == 'f');
+    }
+    else
+    {
+        fprintf(stderr, "Mode string '%s' not recognized\n", mode);
+        return 0;
+    }
+
+    return 1;
+}
+
+void show_version(const char *name)
+{
+    printf("%s version 1.0\n", name);
+}
+
+int main(int argc, char **argv)
+{
+    /*
+     * handling command-line arguments:
+     * i'm going to leave opterr alone (defaults to non-zero)
+     * \this causes getopt to print its own error messages to
+     *  stderr if things go wrong, which is fine.
+     */
+
+    const char *shortopts = "m:vV";
+
+    const struct option longopts[] = {
+        { "mode",    required_argument, NULL, 'm' },
+        { "version", no_argument,       NULL, 'v' },
+        { "verbose", no_argument,       NULL, 'V' },
+        { NULL,      0,                 NULL,  0  }
+    };
+
+    int opt;
+
+    while ((opt = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1)
+    {
+        switch (opt)
+        {
+            case '?':
+                return 1;
+
+            case 'm':
+                if (!set_mode(optarg))
+                    return 1;
+                break;
+
+            case 'v':
+                show_version(argv[0]);
+                return 0;
+
+            case 'V':
+                current_verbose = 1;
+                break;
+        }
+    }
+
+    /* setup signals (mode switch) */
+    signal(SIGINT, &sigint);
+
+
+    char memes[4];
+    fread(memes, 4, 1, stdin);
+    switch (current_mode)
+    {
+        case N:  printf("NORMAL\n"); break;
+        case Z:  printf("NULL\n"); break;
+        case HB: printf("hex to bytes\n"); break;
+        case BH: printf("bytes to hex\n"); break;
+        case IB: printf("bits to bytes\n"); break;
+        case BI: printf("bytes to bits\n"); break;
+    }
+
+    printf("file mode: %i\n", current_mode_f);
+    printf("verbose mode: %i\n", current_verbose);
+
+    return 0;
+}