first-free-port : meilleure gestion des erreurs

README.md

@@ -7,19 +7,19 @@ machines and their disks associated.
 
 ## Why
 
-`qemush` is **daemonless** : no bloaty long running process is needed for
+`qemush` is **daemonless**: no bloaty long running process is needed for
 `qemush` to work.
 
-`qemush` is **lightweight** : it only consists in a shell script to
+`qemush` is **lightweight**: it only consists in a shell script to
 automate repeated tasks and force good practices.
 
-`qemush` needs **few dependencies** : see section
+`qemush` needs **few dependencies**: see section
 [Dependencies](#dependencies) for details.
 
-`qemush` is **hackable** : you can [write your own launching
+`qemush` is **hackable**: you can [write your own launching
 scripts](#writing-a-launching-script) to make it work as intended.
 
-`qemush` is **easy to setup** : you can make it work in a few steps, see
+`qemush` is **easy to setup**: you can make it work in a few steps, see
 section [Installation instructions](#installation-instructions).
 
 ## Good practices?
@@ -49,7 +49,7 @@ need it
 - `screen` - for process supervision
 - `source-highlight` - for syntax highlighting when displaying launching
 scripts
-- any text editor - used for builting function to edit launching scripts
+- any text editor - used for builtin function to edit launching scripts
 
 ## Installation instructions
 
@@ -57,7 +57,7 @@ scripts
 
 `qemush` acts as Unix user `qemu` to manage virtual machines. You need to
 create a system user `qemu` that cannot login, with any home directory,
-in an Unix group of the same name. Example :
+in an Unix group of the same name. Example:
 
 ```sh
 # Example if the qemu user doesn't exist
@@ -72,7 +72,7 @@ For ease of use, you need to grant every user in the `qemu` group via
 ### Add `qemush` in the `PATH`
 
 Use your preferred way to add the `qemush` script to a folder of `PATH`.
-Recommended : copy the script in `/usr/local/bin` to make it effortlessly
+Recommended: copy the script in `/usr/local/bin` to make it effortlessly
 system wide.
 
 ### Extra: add `first-free-port` in `PATH`
@@ -92,7 +92,7 @@ The default text editor used by `qemush` is `nvim`, but it can be
 overriden by the `EDITOR` environment variable.
 
 Run the following command to start editing a launching script by the name
-of your choice :
+of your choice:
 
 ```sh
 qemush edit "$name"
@@ -103,13 +103,13 @@ Example scripts are available in this repo's `qemu/bin` folder.
 ### Launching a virtual machine
 
 Virtual machines are identified by the name of their launching scripts.
-You can launch any machine with the following command :
+You can launch any machine with the following command:
 
 ```sh
 qemush start "$name"
 ```
 
-You can also list all available virtual machines by running this command :
+You can also list all available virtual machines by running this command:
 
 ```sh
 qemush ls

bin/qemush

@@ -93,7 +93,7 @@ public_diskls() {
 public_edit() {
     local file="${bin}/${1}"
     "$EDITOR" "$file"
-    exec chmod u+x "$file"
+    [ -f "$file" ] && exec chmod u+x "$file"
 }
 
 public_rm() {

src/first-free-port.c

@@ -3,6 +3,7 @@
 #include <fcntl.h>
 #include <sysexits.h>
 #include <string.h>
+#include <errno.h>
 
 #define MIN_TCP_PORT 1
 #define TCP_TABLE "/proc/net/tcp"
@@ -12,6 +13,13 @@
 #define LISTENING_HEX "0A"
 #define PORTS_BLOCKS_TO_ALLOW 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
  */
@@ -81,20 +89,25 @@ int main(int argc, char *argv[]) {
     }
 
     if (!is_valid_tcp_port(current_port)) {
-        fprintf(stderr, "Provide a valid TCP port number as first argument.\n");
+        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, "r");
     if (tcp_table_fptr == NULL) {
-        fprintf(stderr, "Error opening the TCP table.\n");
-        return EX_OSFILE;
+        print_error(argv[0], "error opening the TCP table.");
+        return errno;
     }
 
     unsigned short *listening_ports = malloc(PORTS_BLOCKS_TO_ALLOW * sizeof(unsigned short));
     listening_ports = get_listening_ports(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++;
@@ -106,7 +119,7 @@ int main(int argc, char *argv[]) {
         printf("%d\n", current_port);
         return EXIT_SUCCESS;
     } else {
-        fprintf(stderr, "No more ports available. How did you fuck up that bad ???\n");
+        print_error(argv[0], "no more ports available; how did you fuck up that bad ???");
         return EX_TEMPFAIL;
     }
 }