120 lines
2.5 KiB
C++
120 lines
2.5 KiB
C++
#include <luna/StringBuilder.h>
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#include <luna/Vector.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/wait.h>
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#include <unistd.h>
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static Result<Vector<char*>> split_command_into_argv(const char* cmd)
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{
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char* str = strdup(cmd);
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Vector<char*> result;
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char* segment = strtok(str, " \n");
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TRY(result.try_append(segment));
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if (segment == NULL) return result;
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for (;;)
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{
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segment = strtok(NULL, " \n");
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TRY(result.try_append(segment));
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if (segment == NULL) return result;
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}
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return result;
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}
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static Result<String> join_path(const char* str1, const char* str2)
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{
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StringBuilder sb;
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TRY(sb.add(StringView { str1 }));
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TRY(sb.add(StringView { str2 }));
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return sb.string();
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}
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static int execute_in_path(const char* dir, char** argv)
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{
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String path;
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bool ok = join_path(dir, argv[0]).try_move_value_or_error(path, errno);
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if (!ok) return -1;
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int err = errno;
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int status = execv(path.chars(), argv);
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if (errno == ENOENT)
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{
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errno = err;
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return 0;
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}
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return status;
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}
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static int sh_execvp(char** argv)
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{
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if (strchr(argv[0], '/'))
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{
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// Relative paths do not need path resolution.
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return execv(argv[0], argv);
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}
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if (execute_in_path("/bin/", argv) != 0) return -1;
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if (execute_in_path("/sbin/", argv) != 0) return -1;
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if (execute_in_path("/usr/bin/", argv) != 0) return -1;
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if (execute_in_path("/usr/local/bin/", argv) != 0) return -1;
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errno = ENOENT;
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return -1;
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}
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int main()
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{
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while (1)
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{
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fputs("sh$ ", stdout);
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char command[4096];
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char* rc = fgets(command, sizeof(command), stdin);
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if (!rc) return 0;
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if (strspn(command, " \n") == strlen(command)) continue;
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pid_t child = fork();
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if (child < 0)
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{
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perror("fork");
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return 1;
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}
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if (child == 0)
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{
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Vector<char*> argv;
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bool ok = split_command_into_argv(command).try_move_value_or_error(argv, errno);
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if (!ok)
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{
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perror("failed to parse command");
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return 1;
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}
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if (argv[0] == NULL) return 0;
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sh_execvp(argv.data());
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perror(argv[0]);
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return 1;
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}
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if (waitpid(child, NULL, 0) < 0)
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{
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perror("waitpid");
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return 1;
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}
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}
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}
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