Makefile

@@ -1,41 +1,65 @@
-# SRC = source
-# DST = destination
-# *D  = folder containing *
-
 NAME := qemush
+
+# qemu Unix user
 QEMU_USER := qemu
+# sudo as qemu
+SUDO_QEMU := sudo -u $(QEMU_USER)
 
-SRC_BIN := bin/$(NAME)
-DST_BIN := /usr/local/$(SRC_BIN)
+QEMUSH := /usr/local/bin/$(NAME)
+SRC_QEMUSH := bin/$(NAME)
+SRCD := src
 
-SRC_HOME := $(QEMU_USER)
-DST_HOME := $(shell echo ~$(QEMU_USER))
+# This repo's equivalent of effective qemu Unix user home
+SRC_QEMU_HOME := qemu
+SRC_QEMU_BIN := $(SRC_QEMU_HOME)/bin
+SRC_LAUNCHERSD := $(SRC_QEMU_HOME)/launchers
+# Actual qemu Unix user home
+QEMU_HOME := $(shell echo ~$(QEMU_USER))
+QEMU_BIN := $(QEMU_HOME)/bin
+LAUNCHERSD := $(QEMU_HOME)/launchers
 
-SRC_BIND := $(SRC_HOME)/bin
-SRC_LAUNCHERSD := $(SRC_HOME)/launchers
-DST_BIND := $(DST_HOME)/bin
-DST_LAUNCHERSD := $(DST_HOME)/launchers
+# Names of all qemush modules
+SRC_MODULES_NAMES := $(notdir $(wildcard $(SRC_QEMU_BIN)/*))
+# Target location of modules
+MODULES := $(addprefix $(QEMU_BIN)/,$(SRC_MODULES_NAMES))
+# Names of launchers scripts
+SRC_LAUNCHERS_NAMES := $(notdir $(wildcard $(SRC_LAUNCHERSD)/*))
+# Target location of launchers
+LAUNCHERS := $(addprefix $(LAUNCHERSD)/,$(SRC_LAUNCHERS_NAMES))
+# Mode to apply
+BINS_MODE := 740
 
-MODULES_NAMES := $(notdir $(wildcard $(SRC_BIND)/*))
-LAUNCHERS_NAMES := $(notdir $(wildcard $(SRC_LAUNCHERSD)/*))
+# Compiler options
+CC := cc
+CC_OPTIONS = -O2
+# C sources file format
+SRC_FMT := .c
+# Names of C programs to compile
+SRC_C_SOURCES_NAMES := $(notdir $(basename $(wildcard $(SRCD)/*$(SRC_FMT))))
+# Location of C binaries
+C_BINARIES := $(addprefix $(QEMU_BIN)/,$(SRC_C_SOURCES_NAMES))
 
-DST_MODULES := $(addprefix $(DST_BIND)/,$(MODULES_NAMES))
-DST_LAUNCHERS := $(addprefix $(DST_LAUNCHERSD)/,$(LAUNCHERS_NAMES))
-
-QEMUSH_DIRS := $(addprefix $(DST_HOME)/,bin launchers disks sockets/monitors sockets/spice)
+# Directories in ~qemu necessary for qemush to work
+QEMUSH_DIRS_NAMES := bin launchers disks sockets/monitors sockets/spice
+QEMUSH_DIRS := $(addprefix $(QEMU_HOME)/,$(QEMUSH_DIRS_NAMES))
 
 .PHONY: install
 
-install: $(QEMUSH_DIRS) $(DST_MODULES) $(DST_BIN) $(DST_LAUNCHERS)
+install: $(QEMUSH_DIRS) $(MODULES) $(C_BINARIES) $(QEMUSH) $(LAUNCHERS)
 
 $(QEMUSH_DIRS):
-	sudo -u $(QEMU_USER) mkdir -m 750 -p -- $@
+	$(SUDO_QEMU) mkdir -p $@
+	$(SUDO_QEMU) chmod 750 $@
 
-$(DST_BIN): $(SRC_BIN)
-	sudo install -m 755 -- $^ $@
+$(QEMUSH): $(SRC_QEMUSH)
+	sudo install -m 755 $^ $@
 
-$(DST_MODULES): $(DST_HOME)%: $(SRC_HOME)%
-	sudo -u $(QEMU_USER) install -m 740 -- $^ $@
+$(MODULES): $(QEMU_HOME)%: $(SRC_QEMU_HOME)%
+	$(SUDO_QEMU) install -m $(BINS_MODE) $^ $@
 
-$(LAUNCHERS): $(DST_LAUNCHERSD)%: $(SRC_LAUNCHERSD)%
-	sudo -u $(QEMU_USER) install -m 740 -- $^ $@
+$(C_BINARIES): $(QEMU_BIN)%: $(SRCD)%$(SRC_FMT)
+	$(SUDO_QEMU) $(CC) $(CC_OPTIONS) -o $@ $^
+	$(SUDO_QEMU) chmod $(BINS_MODE) $@
+
+$(LAUNCHERS): $(LAUNCHERSD)%: $(SRC_LAUNCHERSD)%
+	$(SUDO_QEMU) install -m $(BINS_MODE) $^ $@

qemu/bin/first-free-port

@@ -1,34 +0,0 @@
-#!/usr/bin/env sh
-#set -x
-
-name=$(basename "$0")
-used_tcp_ports=$(sed 1d /proc/net/tcp \
-    | awk '($4 == "0A") { print $2 }' \
-    | awk -F : '($1 == "00000000" || $1 == "0100007F") { print $2 }' \
-    | perl -e 'foreach my $line (<>) { print hex($line) . "\n"; }'
-)
-
-perror() {
-  >&2 printf "%s: %s\n" "$name" "$*"
-}
-
-port_is_free() {
-  for used_port in $used_tcp_ports; do
-    [ "$port" = "$used_port" ] && return 1
-  done
-
-  :
-}
-
-port=$1
-
-if ! { [ "$port" -gt 0 ] && [ "$port" -lt 65536 ]; } 2> /dev/null; then
-  perror "you must specify a valid TCP port"
-  exit 1
-fi
-
-while ! port_is_free; do
-  port=$((port + 1))
-done
-
-printf %s\\n "$port"

src/first-free-port.c

@@ -0,0 +1,124 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sysexits.h>
+#include <string.h>
+#include <errno.h>
+
+#define MIN_TCP_PORT 1
+#define TCP_TABLE_PATH "/proc/net/tcp"
+#define TCP_TABLE_LINE_LENGTH 151
+#define LOCALHOSTIP_HEX "0100007F"
+#define WILDCARDIP_HEX "00000000"
+#define LISTENING_HEX "0A"
+#define BLOCKS_TO_ALLOC 4
+
+/**
+ * Print a nice error message
+ */
+static void print_error(char *name, const char *message) {
+    fprintf(stderr, "%s: %s\n", name, message);
+}
+
+/**
+ * Get all the listening TCP ports
+ */
+static unsigned short *get_listening_ports(FILE *tcp_table_fptr) {
+    unsigned short *listening_ports = malloc(BLOCKS_TO_ALLOC * sizeof(short));
+    char line[TCP_TABLE_LINE_LENGTH];
+    char delimiter[] = " ";
+    unsigned short len = 0;
+    char *address;
+    char *state;
+    char *field;
+    size_t blocks_allocated = BLOCKS_TO_ALLOC;
+
+    // Skip first line (header)
+    fgets(line, sizeof(line), tcp_table_fptr);
+
+    // Tokenize lines one by one
+    while (fgets(line, sizeof(line), tcp_table_fptr) != NULL) {
+        strtok(line, delimiter);
+
+        address = strtok(NULL, delimiter);
+        strtok(NULL, delimiter);
+        state = strtok(NULL, delimiter);
+        field = strtok(NULL, delimiter);
+        
+        while (field != NULL) {
+            field = strtok(NULL, delimiter);
+        }
+
+        if ((!strncmp(address, LOCALHOSTIP_HEX, 8) || !strncmp(address, WILDCARDIP_HEX, 8)) && !strncmp(state, LISTENING_HEX, 2)) {
+            if (len == blocks_allocated) {
+                blocks_allocated = blocks_allocated + BLOCKS_TO_ALLOC;
+                listening_ports = realloc(listening_ports, blocks_allocated * sizeof(short));
+            }
+            listening_ports[len] = strtol(address + strlen(address) - 4, NULL, 16);
+            len++;
+        }
+    }
+
+    if (len == blocks_allocated) {
+        listening_ports = realloc(listening_ports, blocks_allocated + 1);
+    }
+    listening_ports[len] = 0;
+
+    return listening_ports;
+}
+
+static unsigned char is_port_available(const unsigned short port, const unsigned short *listening_ports) {
+    unsigned short i = 0;
+    while (listening_ports[i] != 0 && listening_ports[i] != port) {
+        i++;
+    }
+    return listening_ports[i] == 0;
+}
+
+static inline unsigned char is_valid_tcp_port(const unsigned short tcp_port) {
+    return tcp_port >= MIN_TCP_PORT;
+}
+
+int main(int argc, char *argv[]) {
+    unsigned short current_port;
+
+    if (argc >= 2) {
+        current_port = atoi(argv[1]);
+    } else {
+        current_port = 0;
+    }
+
+    if (!is_valid_tcp_port(current_port)) {
+        print_error(argv[0], "provide a valid TCP port number as first argument.");
+        return EX_USAGE;
+    }
+
+    // Open TCP table
+    FILE *tcp_table_fptr = fopen(TCP_TABLE_PATH, "r");
+    if (tcp_table_fptr == NULL) {
+        print_error(argv[0], "error opening the TCP table.");
+        return errno;
+    }
+
+    unsigned short *listening_ports = get_listening_ports(tcp_table_fptr);
+
+    if (fclose(tcp_table_fptr) != 0) {
+        print_error(argv[0], "can't close the TCP table.");
+        return errno;
+    }
+
+    // Check if the current port is available, add
+    while (!is_port_available(current_port, listening_ports)) {
+        current_port++;
+    }
+
+    free(listening_ports);
+
+    if (is_valid_tcp_port(current_port)) {
+        printf("%d\n", current_port);
+        return EXIT_SUCCESS;
+    } else {
+        print_error(argv[0], "no more ports available; how did you fuck up that bad ???");
+        return EX_TEMPFAIL;
+    }
+}