diff --git a/compat/win32/path-utils.c b/compat/win32/path-utils.c index 966ef779b9ca9b..a746800cc92d6d 100644 --- a/compat/win32/path-utils.c +++ b/compat/win32/path-utils.c @@ -2,6 +2,9 @@ #include "../../git-compat-util.h" #include "../../environment.h" +#include "../../wrapper.h" +#include "../../strbuf.h" +#include "../../versioncmp.h" int win32_has_dos_drive_prefix(const char *path) { @@ -89,3 +92,199 @@ int win32_fspathcmp(const char *a, const char *b) { return win32_fspathncmp(a, b, (size_t)-1); } + +static int read_at(int fd, char *buffer, size_t offset, size_t size) +{ + if (lseek(fd, offset, SEEK_SET) < 0) { + fprintf(stderr, "could not seek to 0x%x\n", (unsigned int)offset); + return -1; + } + + return read_in_full(fd, buffer, size); +} + +static size_t le16(const char *buffer) +{ + unsigned char *u = (unsigned char *)buffer; + return u[0] | (u[1] << 8); +} + +static size_t le32(const char *buffer) +{ + return le16(buffer) | (le16(buffer + 2) << 16); +} + +/* + * Determine the Go version of a given executable, if it was built with Go. + * + * This recapitulates the logic from + * https://github.com/golang/go/blob/master/src/cmd/go/internal/version/version.go + * (without requiring the user to install `go.exe` to find out). + */ +static ssize_t get_go_version(const char *path, char *go_version, size_t go_version_size) +{ + int fd = open(path, O_RDONLY); + char buffer[1024]; + off_t offset; + size_t num_sections, opt_header_size, i; + char *p = NULL, *q; + ssize_t res = -1; + + if (fd < 0) + return -1; + + if (read_in_full(fd, buffer, 2) < 0) + goto fail; + + /* + * Parse the PE file format, for more details, see + * https://en.wikipedia.org/wiki/Portable_Executable#Layout and + * https://learn.microsoft.com/en-us/windows/win32/debug/pe-format + */ + if (buffer[0] != 'M' || buffer[1] != 'Z') + goto fail; + + if (read_at(fd, buffer, 0x3c, 4) < 0) + goto fail; + + /* Read the `PE\0\0` signature and the COFF file header */ + offset = le32(buffer); + if (read_at(fd, buffer, offset, 24) < 0) + goto fail; + + if (buffer[0] != 'P' || buffer[1] != 'E' || buffer[2] != '\0' || buffer[3] != '\0') + goto fail; + + num_sections = le16(buffer + 6); + opt_header_size = le16(buffer + 20); + offset += 24; /* skip file header */ + + /* + * Validate magic number 0x10b or 0x20b, for full details see + * https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#optional-header-standard-fields-image-only + */ + if (read_at(fd, buffer, offset, 2) < 0 || + ((i = le16(buffer)) != 0x10b && i != 0x20b)) + goto fail; + + offset += opt_header_size; + + for (i = 0; i < num_sections; i++) { + if (read_at(fd, buffer, offset + i * 40, 40) < 0) + goto fail; + + /* + * For full details about the section headers, see + * https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#section-table-section-headers + */ + if ((le32(buffer + 36) /* characteristics */ & ~0x600000) /* IMAGE_SCN_ALIGN_32BYTES */ == + (/* IMAGE_SCN_CNT_INITIALIZED_DATA */ 0x00000040 | + /* IMAGE_SCN_MEM_READ */ 0x40000000 | + /* IMAGE_SCN_MEM_WRITE */ 0x80000000)) { + size_t size = le32(buffer + 16); /* "SizeOfRawData " */ + size_t pointer = le32(buffer + 20); /* "PointerToRawData " */ + + /* + * Skip the section if either size or pointer is 0, see + * https://github.com/golang/go/blob/go1.21.0/src/debug/buildinfo/buildinfo.go#L333 + * for full details. + * + * Merely seeing a non-zero size will not actually do, + * though: he size must be at least `buildInfoSize`, + * i.e. 32, and we expect a UVarint (at least another + * byte) _and_ the bytes representing the string, + * which we expect to start with the letters "go" and + * continue with the Go version number. + */ + if (size < 32 + 1 + 2 + 1 || !pointer) + continue; + + p = malloc(size); + + if (!p || read_at(fd, p, pointer, size) < 0) + goto fail; + + /* + * Look for the build information embedded by Go, see + * https://github.com/golang/go/blob/go1.21.0/src/debug/buildinfo/buildinfo.go#L165-L175 + * for full details. + * + * Note: Go contains code to enforce alignment along a + * 16-byte boundary. In practice, no `.exe` has been + * observed that required any adjustment, therefore + * this here code skips that logic for simplicity. + */ + q = memmem(p, size - 18, "\xff Go buildinf:", 14); + if (!q) + goto fail; + /* + * Decode the build blob. For full details, see + * https://github.com/golang/go/blob/go1.21.0/src/debug/buildinfo/buildinfo.go#L177-L191 + * + * Note: The `endianness` values observed in practice + * were always 2, therefore the complex logic to handle + * any other value is skipped for simplicty. + */ + if ((q[14] == 8 || q[14] == 4) && q[15] == 2) { + /* + * Only handle a Go version string with fewer + * than 128 characters, so the Go UVarint at + * q[32] that indicates the string's length must + * be only one byte (without the high bit set). + */ + if ((q[32] & 0x80) || + !q[32] || + (q + 33 + q[32] - p) > size || + q[32] + 1 > go_version_size) + goto fail; + res = q[32]; + memcpy(go_version, q + 33, res); + go_version[res] = '\0'; + break; + } + } + } + +fail: + free(p); + close(fd); + return res; +} + +void win32_warn_about_git_lfs_on_windows7(int exit_code, const char *argv0) +{ + char buffer[128], *git_lfs = NULL; + const char *p; + + /* + * Git LFS v3.5.1 fails with an Access Violation on Windows 7; That + * would usually show up as an exit code 0xc0000005. For some reason + * (probably because at this point, we no longer have the _original_ + * HANDLE that was returned by `CreateProcess()`) we observe other + * values like 0xb00 and 0x2 instead. Since the exact exit code + * seems to be inconsistent, we check for a non-zero exit status. + */ + if (exit_code == 0) + return; + if (GetVersion() >> 16 > 7601) + return; /* Warn only on Windows 7 or older */ + if (!istarts_with(argv0, "git-lfs ") && + strcasecmp(argv0, "git-lfs")) + return; + if (!(git_lfs = locate_in_PATH("git-lfs"))) + return; + if (get_go_version(git_lfs, buffer, sizeof(buffer)) > 0 && + skip_prefix(buffer, "go", &p) && + versioncmp("1.21.0", p) <= 0) + warning("This program was built with Go v%s\n" + "i.e. without support for this Windows version:\n" + "\n\t%s\n" + "\n" + "To work around this, you can download and install a " + "working version from\n" + "\n" + "\thttps://github.com/git-lfs/git-lfs/releases/tag/" + "v3.4.1\n", + p, git_lfs); + free(git_lfs); +} diff --git a/compat/win32/path-utils.h b/compat/win32/path-utils.h index a561c700e75713..a69483c332c1a7 100644 --- a/compat/win32/path-utils.h +++ b/compat/win32/path-utils.h @@ -34,4 +34,7 @@ int win32_fspathcmp(const char *a, const char *b); int win32_fspathncmp(const char *a, const char *b, size_t count); #define fspathncmp win32_fspathncmp +void win32_warn_about_git_lfs_on_windows7(int exit_code, const char *argv0); +#define warn_about_git_lfs_on_windows7 win32_warn_about_git_lfs_on_windows7 + #endif diff --git a/git-compat-util.h b/git-compat-util.h index f5a9910e55414d..2ad293a3b7e0aa 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -539,6 +539,13 @@ static inline int git_offset_1st_component(const char *path) #define fspathncmp git_fspathncmp #endif +#ifndef warn_about_git_lfs_on_windows7 +static inline void warn_about_git_lfs_on_windows7(int exit_code UNUSED, + const char *argv0 UNUSED) +{ +} +#endif + #ifndef is_valid_path #define is_valid_path(path) 1 #endif diff --git a/run-command.c b/run-command.c index 94f2f3079ff754..7e4e2e7fb6619d 100644 --- a/run-command.c +++ b/run-command.c @@ -575,6 +575,7 @@ static int wait_or_whine(pid_t pid, const char *argv0, int in_signal) */ code += 128; } else if (WIFEXITED(status)) { + warn_about_git_lfs_on_windows7(status, argv0); code = WEXITSTATUS(status); } else { if (!in_signal)