grub2/0323-hostdisk-work-around-proc-not-reporting-size.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Robbie Harwood <rharwood@redhat.com>
Date: Thu, 9 Mar 2023 11:18:19 -0500
Subject: [PATCH] hostdisk: work around /proc not reporting size
fstat(2) of files in /proc will yield st_size == 0 regardless of file
contents. Use a negative value in grub_file_t's size to denote "ignore"
and plumb through.
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
---
grub-core/kern/file.c | 28 ++++++++++++++++------------
grub-core/lib/progress.c | 2 +-
grub-core/osdep/unix/hostdisk.c | 6 ++++++
3 files changed, 23 insertions(+), 13 deletions(-)
diff --git a/grub-core/kern/file.c b/grub-core/kern/file.c
index 868ce3b63e..4ea6d1ce95 100644
--- a/grub-core/kern/file.c
+++ b/grub-core/kern/file.c
@@ -172,26 +172,30 @@ grub_file_read (grub_file_t file, void *buf, grub_size_t len)
grub_disk_read_hook_t read_hook;
void *read_hook_data;
- if (file->offset > file->size)
- {
- grub_error (GRUB_ERR_OUT_OF_RANGE,
- N_("attempt to read past the end of file"));
- return -1;
- }
-
if (len == 0)
return 0;
- if (len > file->size - file->offset)
- len = file->size - file->offset;
+#ifdef GRUB_MACHINE_EMU
+ if (file->size >= 0)
+ {
+#endif
+ if (file->offset > file->size)
+ {
+ grub_error (GRUB_ERR_OUT_OF_RANGE,
+ N_("attempt to read past the end of file"));
+ return -1;
+ }
+
+ if (len > file->size - file->offset)
+ len = file->size - file->offset;
+#ifdef GRUB_MACHINE_EMU
+ }
+#endif
/* Prevent an overflow. */
if ((grub_ssize_t) len < 0)
len >>= 1;
- if (len == 0)
- return 0;
-
read_hook = file->read_hook;
read_hook_data = file->read_hook_data;
if (!file->read_hook)
diff --git a/grub-core/lib/progress.c b/grub-core/lib/progress.c
index 4b7cbbca6d..f3226b6898 100644
--- a/grub-core/lib/progress.c
+++ b/grub-core/lib/progress.c
@@ -71,7 +71,7 @@ grub_file_progress_hook_real (grub_disk_addr_t sector __attribute__ ((unused)),
* 100ULL * 1000ULL,
now - file->last_progress_time, 0);
- if (file->size == 0)
+ if (file->size <= 0)
percent = 100;
else
percent = grub_divmod64 (100 * file->progress_offset,
diff --git a/grub-core/osdep/unix/hostdisk.c b/grub-core/osdep/unix/hostdisk.c
index 3a00d7451a..e5f4b4d5f9 100644
--- a/grub-core/osdep/unix/hostdisk.c
+++ b/grub-core/osdep/unix/hostdisk.c
@@ -71,6 +71,12 @@ grub_util_get_fd_size (grub_util_fd_t fd, const char *name, unsigned *log_secsiz
if (log_secsize)
*log_secsize = 9;
+#ifdef GRUB_MACHINE_EMU
+ /* /proc doesn't behave itself and gives 0 for file sizes to stat. */
+ if (st.st_size == 0 && !grub_strncmp ("/proc", name, 5))
+ return -1;
+#endif
+
return st.st_size;
}