From 6a6b76cc44c98a39d3e718aa2056e2e12b609615 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Tue, 18 Aug 2020 10:57:04 +0200 Subject: vc_screen: extract vcs_read_buf And finally, move the attributes buffer handling to a separate function. Leaving vcs_read quite compact. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20200818085706.12163-14-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vc_screen.c | 146 ++++++++++++++++++++++++--------------------- 1 file changed, 78 insertions(+), 68 deletions(-) diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index ad015cd4e82f..c178a1611223 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -297,14 +297,81 @@ static void vcs_read_buf_noattr(const struct vc_data *vc, char *con_buf, } } +static unsigned int vcs_read_buf(const struct vc_data *vc, char *con_buf, + unsigned int pos, unsigned int count, bool viewed, + unsigned int *skip) +{ + u16 *org, *con_buf16; + unsigned int col, maxcol = vc->vc_cols; + unsigned int filled = count; + + if (pos < HEADER_SIZE) { + /* clamp header values if they don't fit */ + con_buf[0] = min(vc->vc_rows, 0xFFu); + con_buf[1] = min(vc->vc_cols, 0xFFu); + getconsxy(vc, con_buf + 2); + + *skip += pos; + count += pos; + if (count > CON_BUF_SIZE) { + count = CON_BUF_SIZE; + filled = count - pos; + } + + /* Advance state pointers and move on. */ + count -= min(HEADER_SIZE, count); + pos = HEADER_SIZE; + con_buf += HEADER_SIZE; + /* If count >= 0, then pos is even... */ + } else if (pos & 1) { + /* + * Skip first byte for output if start address is odd. Update + * region sizes up/down depending on free space in buffer. + */ + (*skip)++; + if (count < CON_BUF_SIZE) + count++; + else + filled--; + } + + if (!count) + return filled; + + pos -= HEADER_SIZE; + pos /= 2; + col = pos % maxcol; + + org = screen_pos(vc, pos, viewed); + pos += maxcol - col; + + /* + * Buffer has even length, so we can always copy character + attribute. + * We do not copy last byte to userspace if count is odd. + */ + count = (count + 1) / 2; + con_buf16 = (u16 *)con_buf; + + while (count) { + *con_buf16++ = vcs_scr_readw(vc, org++); + count--; + if (++col == maxcol) { + org = screen_pos(vc, pos, viewed); + col = 0; + pos += maxcol; + } + } + + return filled; +} + static ssize_t vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct inode *inode = file_inode(file); struct vc_data *vc; struct vcs_poll_data *poll; - u16 *org; - unsigned int read, col, maxcol; + unsigned int read; ssize_t ret; char *con_buf; loff_t pos; @@ -341,8 +408,7 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) read = 0; ret = 0; while (count) { - char *con_buf0, *con_buf_start; - unsigned int this_round, orig_count, p = pos; + unsigned int this_round, skip = 0; int size; /* Check whether we are above size each round, @@ -370,9 +436,6 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) * attempt to move it to userspace. */ - con_buf_start = con_buf0 = con_buf; - orig_count = this_round; - maxcol = vc->vc_cols; if (uni_mode) { ret = vcs_read_buf_uni(vc, con_buf, pos, this_round, viewed); @@ -382,61 +445,8 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) vcs_read_buf_noattr(vc, con_buf, pos, this_round, viewed); } else { - if (p < HEADER_SIZE) { - /* clamp header values if they don't fit */ - con_buf0[0] = min(vc->vc_rows, 0xFFu); - con_buf0[1] = min(vc->vc_cols, 0xFFu); - getconsxy(vc, con_buf0 + 2); - - con_buf_start += p; - this_round += p; - if (this_round > CON_BUF_SIZE) { - this_round = CON_BUF_SIZE; - orig_count = this_round - p; - } - - /* Advance state pointers and move on. */ - this_round -= min(HEADER_SIZE, this_round); - p = HEADER_SIZE; - con_buf0 = con_buf + HEADER_SIZE; - /* If this_round >= 0, then p is even... */ - } else if (p & 1) { - /* Skip first byte for output if start address is odd - * Update region sizes up/down depending on free - * space in buffer. - */ - con_buf_start++; - if (this_round < CON_BUF_SIZE) - this_round++; - else - orig_count--; - } - if (this_round > 0) { - unsigned short *tmp_buf = (unsigned short *)con_buf0; - - p -= HEADER_SIZE; - p /= 2; - col = p % maxcol; - - org = screen_pos(vc, p, viewed); - p += maxcol - col; - - /* Buffer has even length, so we can always copy - * character + attribute. We do not copy last byte - * to userspace if this_round is odd. - */ - this_round = (this_round + 1) >> 1; - - while (this_round) { - *tmp_buf++ = vcs_scr_readw(vc, org++); - this_round --; - if (++col == maxcol) { - org = screen_pos(vc, p, viewed); - col = 0; - p += maxcol; - } - } - } + this_round = vcs_read_buf(vc, con_buf, pos, this_round, + viewed, &skip); } /* Finally, release the console semaphore while we push @@ -447,18 +457,18 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) */ console_unlock(); - ret = copy_to_user(buf, con_buf_start, orig_count); + ret = copy_to_user(buf, con_buf + skip, this_round); console_lock(); if (ret) { - read += (orig_count - ret); + read += this_round - ret; ret = -EFAULT; break; } - buf += orig_count; - pos += orig_count; - read += orig_count; - count -= orig_count; + buf += this_round; + pos += this_round; + read += this_round; + count -= this_round; } *ppos += read; if (read) -- cgit 1.4.1