streamutils

commit eb3c0123f187e0ef6696c8f1d74994fe5c162e74
Author: Charlie Stanton <charlie@shtanton.xyz>
Date:   Wed, 17 Aug 2022 12:45:19 +0100

Initial commit

Implements version 0.1.0 of roundrobin

Diffstat:
A
.gitignore
 | 
1
+
A
Makefile
 | 
9
+++++++++
A
src/roundrobin.c
 | 
101
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 111 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+bin
diff --git a/Makefile b/Makefile
@@ -0,0 +1,9 @@
+PROGRAMS=roundrobin
+BINARIES=$(patsubst %, bin/%, $(PROGRAMS))
+
+all: $(BINARIES)
+
+bin/%: src/%.c
+	$(CC) $(CFLAGS) $^ -o $@
+	
+.PHONY: all
diff --git a/src/roundrobin.c b/src/roundrobin.c
@@ -0,0 +1,101 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct {
+  size_t length;
+  size_t capacity;
+  FILE **writers;
+} outputs;
+
+void append_output(FILE *writer) {
+  if (outputs.length >= outputs.capacity) {
+    outputs.capacity *= 2;
+    outputs.writers = realloc(outputs.writers, outputs.capacity * sizeof(FILE **));
+    if (outputs.writers == NULL) {
+      fprintf(stderr, "Out of memory\n");
+      exit(1);
+    }
+  }
+  outputs.writers[outputs.length++] = writer;
+}
+
+int main(int argc, char *argv[]) {
+  int c;
+  size_t output_index = 0;
+  char separator = '\n';
+  FILE *writer;
+  
+  outputs.length = 0;
+  outputs.capacity = 4;
+  outputs.writers = malloc(4 * sizeof(FILE **));
+  if (outputs.writers == NULL) {
+    fprintf(stderr, "Out of memory\n");
+    return 1;
+  }
+  
+  if (argc <= 1) {
+    fprintf(stderr, "Missing output files\n");
+    return 1;
+  }
+  
+  size_t i;
+  for (i = 1; i < argc; i++) {
+    if (argv[i][0] != '-') {
+      fprintf(stderr, "Expected flag, found: \"%s\"\n", argv[i]);
+      return 1;
+    }
+    
+    if (argv[i][1] != '\0' && argv[i][2] != '\0') {
+      fprintf(stderr, "Invalid flag: \"%s\"", argv[i]);
+      return 1;
+    }
+
+    switch (argv[i][1]) {
+      case 'e':
+        if (++i >= argc) {
+          fprintf(stderr, "Missing file after -f\n");
+          return 1;
+        }
+        writer = popen(argv[i], "w");
+        if (writer == NULL) {
+          fprintf(stderr, "Error running command: %s\n", argv[i]);
+          return 1;
+        }
+        append_output(writer);
+        break;
+      case 'f':
+        if (++i >= argc) {
+          fprintf(stderr, "Missing file after -f\n");
+          return 1;
+        }
+        writer = fopen(argv[i], "w");
+        if (writer == NULL) {
+          fprintf(stderr, "Error opening file %s\n", argv[i]);
+          return 1;
+        }
+        append_output(writer);
+        break;
+      default:
+        fprintf(stderr, "Invalid flag: \"%s\"\n", argv[i]);
+        return 1;
+    }
+  }
+
+  for (;;) {
+    c = getchar();
+    if (c == EOF) {
+      break;
+    }
+    
+    if (fputc(c, outputs.writers[output_index]) == EOF) {
+      fprintf(stderr, "Error writing to output %lu\n", output_index);
+      return 1;
+    }
+
+    if (c == separator) {
+      fflush(outputs.writers[output_index]);
+      output_index++;
+      output_index %= outputs.length;
+    }
+  }
+}