140 lines
2.9 KiB
C++
140 lines
2.9 KiB
C++
#include <pwd.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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static struct passwd pwd;
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static FILE* f { nullptr };
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static char buf[4096];
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// Variant of strtok that returns empty tokens when there are several delimiters, instead of skipping all at once.
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// Example:
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// strtok("hello:world::!:", ":") -> "hello", "world", "!"
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// _strtok_once("hello:world::!:", ":") -> "hello", "world", "", "!"
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static char* _strtok_once(char* str, const char* delim)
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{
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static char* s = nullptr;
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if (str) s = str;
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if (!s) return nullptr;
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if (*s)
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{
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if (*s == 0) return nullptr;
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size_t use = strcspn(s, delim);
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char* result = s;
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if (s[use] != 0)
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{
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s[use] = 0;
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s += (use + 1);
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}
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else { s = nullptr; }
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return result;
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}
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return nullptr;
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}
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extern "C"
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{
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struct passwd* getpwent()
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{
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if (!f)
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{
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f = fopen("/etc/passwd", "r");
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if (!f) return nullptr;
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}
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while (true)
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{
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char* rc = fgets(buf, sizeof(buf), f);
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if (!rc) return nullptr;
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char* name = _strtok_once(rc, ":\n");
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if (!name) continue;
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char* passwd = _strtok_once(nullptr, ":\n");
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if (!passwd) continue;
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char* uid = _strtok_once(nullptr, ":\n");
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if (!uid) continue;
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char* gid = _strtok_once(nullptr, ":\n");
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if (!gid) continue;
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char* gecos = _strtok_once(nullptr, ":\n");
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if (!gecos) continue;
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char* dir = _strtok_once(nullptr, ":\n");
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if (!dir) continue;
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char* shell = _strtok_once(nullptr, ":\n");
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if (!shell) continue;
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pwd.pw_name = name;
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pwd.pw_passwd = passwd;
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pwd.pw_uid = (uid_t)strtoul(uid, NULL, 10);
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pwd.pw_gid = (gid_t)strtoul(gid, NULL, 10);
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pwd.pw_gecos = gecos;
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pwd.pw_dir = dir;
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pwd.pw_shell = shell;
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return &pwd;
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}
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}
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struct passwd* getpwnam(const char* name)
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{
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setpwent();
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struct passwd* entry;
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while ((entry = getpwent()))
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{
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if (!strcmp(entry->pw_name, name))
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{
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endpwent();
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return entry;
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}
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}
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endpwent();
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return entry;
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}
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struct passwd* getpwuid(uid_t uid)
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{
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setpwent();
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struct passwd* entry;
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while ((entry = getpwent()))
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{
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if (entry->pw_uid == uid)
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{
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endpwent();
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return entry;
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}
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}
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endpwent();
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return entry;
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}
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void setpwent()
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{
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if (f) rewind(f);
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}
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void endpwent()
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{
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if (f)
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{
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fclose(f);
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f = nullptr;
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}
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}
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}
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