LibC: Implement getgr{gid,nam}_r
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@ -1,162 +1,213 @@
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#include <BAN/StringView.h>
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#include <BAN/Vector.h>
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#include <ctype.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <grp.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/types.h>
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#include <string.h>
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#include <unistd.h>
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static struct stat s_group_st;
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static char* s_group_mmap = nullptr;
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static int s_group_fd = -1;
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static FILE* s_grent_fp = nullptr;
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static group s_grent_struct;
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static struct group s_group;
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static char* s_grent_buffer = nullptr;
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static size_t s_grent_buffer_size = 0;
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id_t parse_id(BAN::StringView string)
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void endgrent(void)
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{
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id_t id = 0;
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for (char c : string)
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{
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if (!isdigit(c))
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return -1;
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id = (id * 10) + (c - '0');
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}
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return id;
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if (s_grent_fp)
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fclose(s_grent_fp);
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s_grent_fp = nullptr;
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if (s_grent_buffer)
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free(s_grent_buffer);
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s_grent_buffer = nullptr;
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}
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static bool open_group_file()
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void setgrent(void)
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{
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if (s_group_fd == -1)
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s_group_fd = open("/etc/group", O_RDONLY);
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if (s_group_fd == -1)
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return false;
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if (fstat(s_group_fd, &s_group_st) == -1)
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return false;
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if (s_group_mmap == nullptr || s_group_mmap == MAP_FAILED)
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s_group_mmap = (char*)mmap(nullptr, s_group_st.st_size, PROT_READ, MAP_PRIVATE, s_group_fd, 0);
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if (s_group_mmap == MAP_FAILED)
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return false;
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s_group.gr_name = nullptr;
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s_group.gr_mem = nullptr;
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return true;
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if (!s_grent_fp)
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return;
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fseek(s_grent_fp, 0, SEEK_SET);
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}
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struct group* fill_group(const BAN::Vector<BAN::StringView>& parts)
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static int getgrent_impl(FILE* fp, struct group* grp, char* buffer, size_t bufsize, struct group** result)
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{
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if (parts.size() != 4)
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return nullptr;
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if (s_group.gr_name)
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for (;;)
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{
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free(s_group.gr_name);
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s_group.gr_name = nullptr;
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}
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if (s_group.gr_mem)
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{
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for (size_t i = 0; s_group.gr_mem && s_group.gr_mem[i]; i++)
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free(s_group.gr_mem[i]);
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free(s_group.gr_mem);
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s_group.gr_mem = nullptr;
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}
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auto groups_or_error = parts[3].split(',');
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if (groups_or_error.is_error())
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return nullptr;
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auto groups = groups_or_error.release_value();
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s_group.gr_gid = parse_id(parts[2]);
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if (s_group.gr_gid == -1)
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return nullptr;
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s_group.gr_name = (char*)malloc(parts[0].size() + 1);
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if (s_group.gr_name == nullptr)
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return nullptr;
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memcpy(s_group.gr_name, parts[0].data(), parts[0].size());
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s_group.gr_name[parts[0].size()] = '\0';
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s_group.gr_mem = (char**)malloc((groups.size() + 1) * sizeof(char*));
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if (s_group.gr_mem == nullptr)
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return nullptr;
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for (size_t i = 0; i < groups.size(); i++)
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{
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s_group.gr_mem[i] = (char*)malloc(groups[i].size() + 1);
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if (s_group.gr_mem[i] == nullptr)
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if (fgets(buffer, bufsize, fp) == nullptr)
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{
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for (size_t j = 0; j < i; j++)
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free(s_group.gr_mem[j]);
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free(s_group.gr_mem);
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s_group.gr_mem = nullptr;
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return nullptr;
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if (ferror(fp))
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return errno;
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*result = nullptr;
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return 0;
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}
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memcpy(s_group.gr_mem[i], groups[i].data(), groups[i].size());
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s_group.gr_mem[i][groups[i].size()] = '\0';
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}
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s_group.gr_mem[groups.size()] = nullptr;
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return &s_group;
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const size_t line_len = strlen(buffer);
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if (line_len == 0)
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continue;
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if (buffer[line_len - 1] == '\n')
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buffer[line_len - 1] = '\0';
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else if (!feof(fp))
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return (errno = ERANGE);
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#define GET_STRING() ({ \
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ptr = strchr(ptr, ':'); \
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if (ptr == nullptr) \
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continue; \
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*ptr++ = '\0'; \
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})
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#define GET_INT() ({ \
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if (!isdigit(*ptr)) \
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continue; \
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long val = 0; \
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while (isdigit(*ptr)) \
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val = (val * 10) + (*ptr++ - '0'); \
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if (*ptr != ':') \
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continue; \
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*ptr++ = '\0'; \
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val; \
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})
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char* ptr = buffer;
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grp->gr_name = ptr;
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GET_STRING();
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grp->gr_passwd = ptr;
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GET_STRING();
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grp->gr_gid = GET_INT();
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size_t offset = line_len + 1;
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if (auto rem = offset % alignof(char*))
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offset += alignof(char*) - rem;
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grp->gr_mem = reinterpret_cast<char**>(buffer + offset);
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const size_t mem_max = (bufsize - offset) / sizeof(char*);
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size_t mem_idx = 0;
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while (*ptr && mem_idx + 1 <= mem_max)
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{
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grp->gr_mem[mem_idx++] = ptr;
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ptr = strchrnul(ptr, ',');
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if (*ptr == ',')
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*ptr++ = '\0';
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}
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if (mem_idx + 1 > mem_max)
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return (errno = ERANGE);
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grp->gr_mem[mem_idx] = nullptr;
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*result = grp;
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return 0;
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}
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}
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struct group* getgrnam(const char* name)
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struct group* getgrent(void)
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{
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if (s_group_mmap == nullptr || s_group_mmap == MAP_FAILED)
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if (!open_group_file())
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return nullptr;
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off_t start = 0;
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off_t end = 0;
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while (start < s_group_st.st_size)
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if (s_grent_fp == nullptr)
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{
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while (end < s_group_st.st_size && s_group_mmap[end] != '\n')
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end++;
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BAN::StringView line(s_group_mmap + start, end - start);
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start = ++end;
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auto parts_or_error = line.split(':', true);
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if (parts_or_error.is_error())
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s_grent_fp = fopen("/etc/group", "r");
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if (s_grent_fp == nullptr)
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return nullptr;
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auto parts = parts_or_error.release_value();
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if (parts.size() == 4 && parts[0] == name)
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return fill_group(parts);
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}
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return nullptr;
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if (s_grent_buffer == nullptr)
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{
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long size = sysconf(_SC_GETGR_R_SIZE_MAX);
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if (size == -1)
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size = 512;
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s_grent_buffer = static_cast<char*>(malloc(size));
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if (s_grent_buffer == nullptr)
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return nullptr;
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s_grent_buffer_size = size;
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}
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const off_t old_offset = ftello(s_grent_fp);
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group* result;
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for (;;)
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{
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const int error = getgrent_impl(s_grent_fp, &s_grent_struct, s_grent_buffer, s_grent_buffer_size, &result);
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if (error == 0)
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break;
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fseeko(s_grent_fp, old_offset, SEEK_SET);
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if (error != ERANGE)
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return nullptr;
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const size_t new_size = s_grent_buffer_size * 2;
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char* new_buffer = static_cast<char*>(realloc(s_grent_buffer, new_size));
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if (new_buffer == nullptr)
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return nullptr;
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s_grent_buffer = new_buffer;
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s_grent_buffer_size = new_size;
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}
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return result;
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}
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struct group* getgrgid(gid_t gid)
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{
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if (s_group_mmap == nullptr || s_group_mmap == MAP_FAILED)
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if (!open_group_file())
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return nullptr;
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off_t start = 0;
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off_t end = 0;
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while (start < s_group_st.st_size)
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{
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while (end < s_group_st.st_size && s_group_mmap[end] != '\n')
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end++;
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BAN::StringView line(s_group_mmap + start, end - start);
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start = ++end;
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auto parts_or_error = line.split(':', true);
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if (parts_or_error.is_error())
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return nullptr;
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auto parts = parts_or_error.release_value();
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if (parts.size() == 4 && parse_id(parts[2]) == gid)
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return fill_group(parts);
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}
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group* grp;
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setgrent();
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while ((grp = getgrent()))
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if (grp->gr_gid == gid)
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return grp;
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return nullptr;
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}
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struct group* getgrnam(const char* name)
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{
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group* grp;
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setgrent();
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while ((grp = getgrent()))
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if (strcmp(grp->gr_name, name) == 0)
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return grp;
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return nullptr;
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}
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int getgrgid_r(gid_t gid, struct group* grp, char* buffer, size_t bufsize, struct group** result)
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{
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FILE* fp = fopen("/etc/group", "r");
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if (fp == nullptr)
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return errno;
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int ret = 0;
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for (;;)
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{
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if ((ret = getgrent_impl(fp, grp, buffer, bufsize, result)))
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break;
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if (*result == nullptr)
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break;
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if (grp->gr_gid == gid)
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break;
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}
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fclose(fp);
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return ret;
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}
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int getgrnam_r(const char* name, struct group* grp, char* buffer, size_t bufsize, struct group** result)
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{
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FILE* fp = fopen("/etc/group", "r");
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if (fp == nullptr)
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return errno;
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int ret = 0;
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for (;;)
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{
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if ((ret = getgrent_impl(fp, grp, buffer, bufsize, result)))
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break;
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if (*result == nullptr)
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break;
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if (strcmp(grp->gr_name, name) == 0)
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break;
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}
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fclose(fp);
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return ret;
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}
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@ -13,15 +13,16 @@ __BEGIN_DECLS
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struct group
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{
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char* gr_name; /* The name of the group. */
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gid_t gr_gid; /* Numerical group ID. */
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char** gr_mem; /* Pointer to a null-terminated array of character pointers to member names. */
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char* gr_name; /* The name of the group. */
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char* gr_passwd;/* The password of the group */
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gid_t gr_gid; /* Numerical group ID. */
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char** gr_mem; /* Pointer to a null-terminated array of character pointers to member names. */
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};
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void endgrent(void);
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struct group* getgrent(void);
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struct group* getgrgid(gid_t gid);
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int getgrgit_r(gid_t gid, struct group* grp, char* buffer, size_t bufsize, struct group** result);
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int getgrgid_r(gid_t gid, struct group* grp, char* buffer, size_t bufsize, struct group** result);
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struct group* getgrnam(const char* name);
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int getgrnam_r(const char* name, struct group* grp, char* buffer, size_t bufsize, struct group** result);
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void setgrent(void);
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