rc Rand/crypto utility

user/rc/.gitignore

@@ -0,0 +1,2 @@
+*.o
+rc

user/rc/Makefile

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+include $(ROOT)/mk/grabsrc.mk
+include ../Makefile.inc
+
+.PHONY: all clean
+
+TARGET := rc
+
+LDFLAGS += -L$(ROOT)/ulib -l:libulib.a
+
+SRCFILES := $(call GRABSRC, .)
+CFILES := $(call GET_CFILES, $(SRCFILES))
+OBJ := $(call GET_OBJ, $(SRCFILES))
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+all: $(TARGET)
+
+$(TARGET): $(OBJ)
+	$(LD) $^ $(LDFLAGS) -o $@
+	echo $$(realpath $(TARGET)) >> $(FILES)
+
+clean:
+	rm -f $(OBJ) $(TARGET)

user/rc/main.c

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+#include <stdint.h>
+#include <stddef.h>
+#include <ulib.h>
+
+#define CMDS(X)                 \
+  X(rr)                         \
+
+void main(void) {
+  if (argslen() == 0) {
+    return;
+  }
+
+  char *cmd = args()[0];
+
+  #define X(name) if (string_strcmp(cmd, #name) == 0) { \
+    extern void rc_ ## name(void); \
+    rc_ ## name(); \
+    return; \
+  }
+  CMDS(X)
+  #undef X
+
+  uprintf("rc: unknown command %s\n", cmd);
+}

user/rc/rr.c

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+#include <stddef.h>
+#include <stdint.h>
+#include <ulib.h>
+
+int32_t rr(int32_t min, int32_t max) {
+  if (max <= min)
+    return min;
+
+  uint32_t range = (uint32_t)(max - min + 1);
+  uint32_t val;
+  int32_t rnd;
+
+  for (size_t i = 0; i < 10; i++) {
+    rnd = rand();
+    if (rnd == -1)
+      continue;
+
+    val = (uint32_t)rnd;
+
+    uint32_t limit = (uint32_t)(-range) % range;
+    if (val >= limit) {
+      return min + (val % range);
+    }
+  }
+
+  return -1;
+}
+
+void rc_rr(void) {
+  if (argslen() < 3) {
+    uprintf("rc: Not enough arguments\n");
+    return;
+  }
+
+  char *beginstr = *(args()+1);
+  char *endstr = *(args()+2);
+
+  char *endb;
+  long begin = string_conv_strtol(beginstr, &endb, 10);
+  char *ende;
+  long end = string_conv_strtol(endstr, &ende, 10);
+
+  int32_t r = rr(begin, end);
+  if (rr == -1) {
+    uprintf("rc: failed to generate random number in range\n");
+    return;
+  }
+
+  uprintf("%d\n", r);
+}