Initial commit of terminus source code

This version is fully working, though it is still lacking in some
functionality.

2 files changed, 207 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..cdae433
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,7 @@
+out = terminus
+
+all:
+	cc src/main.c -lm -o $(out)
+
+debug:
+	make all dbg="-g"
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..c36ac6e
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,200 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <math.h>
+
+//
+// Converts the given day count to seconds (multiplies by the number of seconds
+// in a day, 86400).
+//
+// @param days Day count to convert to seconds
+//
+// @return long Number of total seconds in the given day duration
+//
+long days_to_seconds(int days) {
+  return days * 86400;
+}
+
+
+//
+// Converts the given "string integer" to a long datatype. This is useful for
+// programs that take command line arguments from the user and they need to
+// treats those arguments like actual numbers.
+//
+// @param intstr Integer string
+//
+// @return long The integer represented by the given string
+//
+long ctoi(char* intstr) {
+  // TODO: This doesn't work yet
+  int i = 0;
+  long out = 0;
+
+  while(intstr[i] != '\0') {
+    //printf("%d\n", intstr[i] - 48);
+    if(intstr[i] == '0') {
+      out += pow(10,i);
+    } else {
+      out += (intstr[i] - 48) + pow(10,i);
+    }
+    i++;
+  }
+  return out;
+}
+
+
+//
+//
+//
+int get_user_home(char* out) {
+  if(getenv("HOME") != NULL) {
+    strcpy(out, getenv("HOME"));
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+
+//
+// Writes the current timestamp to the specified lastlogin file
+//
+// @param path Path to the lastlogin file
+//
+// @return int Status of the write operation
+//
+int write_lastlogin(char* path) {
+  FILE* f = fopen(path, "w+");
+
+  // Exit if file cannot be opened for writing
+  if(f == NULL) { return 1; }
+
+  // Write the current time
+  fprintf(f, "%d", time(NULL));
+
+  fclose(f);
+  return 0;
+}
+
+
+//
+// Gets the time_t value contained in the specified lastlogin file.
+//
+// @param lastlogin_path Path to the lastlogin file to be read
+// @param lastlogin Output time_t variable
+//
+// @return int Status of reading the lastlogin file
+//
+int get_lastlogin(char* lastlogin_path, time_t* lastlogin) {
+  // File pointer to lastlogin file (used for reading and writing)
+  FILE* lastlogin_file;
+  // String contents of the lastlogin file
+  char lastlogin_str[32];
+
+  // Attempt read lastlogin file contents
+  lastlogin_file = fopen(lastlogin_path, "r");
+  
+  if(lastlogin_file == NULL) {
+    return 1;
+  } else {
+    // Read the lastlogin file and set its value to lastlogin
+    fgets(lastlogin_str, 32, lastlogin_file);
+    *lastlogin = atoi(lastlogin_str);
+    fclose(lastlogin_file);
+  }
+  return 0;
+}
+
+
+//
+// Executes the specified command, printing the output.
+// Note that this does read the calling shell's environmental variables, and so
+// absolute paths are not necessary if the command targets an executable in
+// PATH.
+//
+// @param cmd Command to be executed and output to be printed
+//
+// @return int Execution status of the command
+//             Note that if the command fails execution at start, -1 is
+//             returned.
+//
+int exec_cmd(char* cmd) {
+  FILE* p = popen(cmd, "r");
+  if(p == NULL) { return -1; }
+
+  // Buffer for each line
+  char line[256];
+  // For each line, print the output
+  while (fgets(line, sizeof(line)-1, p) != NULL) {
+    printf("%s", line);
+  }
+
+  return pclose(p);
+}
+
+
+//
+// Ye olde main function
+//
+int main(int argc, char* argv[]) {
+  char home[128];
+  int days;
+  char* cmd;
+  // Expected path to lastlogin file
+  char lastlogin_path[256];
+  // Time-related variables
+  time_t now;
+  time_t threshold;
+  time_t lastlogin;
+
+  if(argc < 3) {
+    printf(
+      "Please specify a timeout threshold (in days) as well as a command\n"
+      "or commands to be run if the threshold is exceeded.\n\n"
+      "Example:\n"
+      "  terminus 5 '<command to execute>'\n\n"
+      "This example will execute the given command if the user has not\n"
+      "logged in in the last 5 days.\n\n"
+    );
+    return 1;
+  }
+
+  // Get program arguments
+  days = atoi(argv[1]);
+  cmd = argv[2];
+
+  // Compose path to lastlogin file
+  get_user_home(home);
+  strcpy(lastlogin_path, home);
+  strcat(lastlogin_path, "/.lastlogin");
+
+  // Set time-related values
+  now = time(NULL);
+  threshold = days_to_seconds(days);
+  if(get_lastlogin(lastlogin_path, &lastlogin) == 1) {
+    // Create lastlogin file since it doesn't exist
+    printf("Lastlogin file could not be read. Writing\n");
+    if(write_lastlogin(lastlogin_path) == 1) {
+      printf("Failure writing lastlogin\n");
+      return 1;
+    }
+    // Go ahead and set lastlogin time, since writing it means we're using
+    // "now".
+    lastlogin = time(NULL);
+  }
+
+  // Determine if I'm dead
+  if((now - lastlogin) > threshold) {
+    printf("You're dead!\n");
+    exec_cmd(cmd);
+  } else {
+    if(write_lastlogin(lastlogin_path) == 1) {
+      printf("Failure writing lastlogin\n");
+      return 1;
+    }
+    printf("You're not dead!\n");
+  }
+  
+  return 0;
+}